diff --git a/packages/react-art/src/ReactARTHostConfig.js b/packages/react-art/src/ReactARTHostConfig.js
index ec702bf9a70d4..47bced8a1274a 100644
--- a/packages/react-art/src/ReactARTHostConfig.js
+++ b/packages/react-art/src/ReactARTHostConfig.js
@@ -436,24 +436,6 @@ export function getInstanceFromNode(node) {
   throw new Error('Not implemented.');
 }
 
-export function isOpaqueHydratingObject(value: mixed): boolean {
-  throw new Error('Not implemented.');
-}
-
-export function makeOpaqueHydratingObject(
-  attemptToReadValue: () => void,
-): OpaqueIDType {
-  throw new Error('Not implemented.');
-}
-
-export function makeClientId(): OpaqueIDType {
-  throw new Error('Not implemented.');
-}
-
-export function makeClientIdInDEV(warnOnAccessInDEV: () => void): OpaqueIDType {
-  throw new Error('Not implemented.');
-}
-
 export function beforeActiveInstanceBlur(internalInstanceHandle: Object) {
   // noop
 }
diff --git a/packages/react-debug-tools/src/ReactDebugHooks.js b/packages/react-debug-tools/src/ReactDebugHooks.js
index eed8c46df7d6d..895e75359867c 100644
--- a/packages/react-debug-tools/src/ReactDebugHooks.js
+++ b/packages/react-debug-tools/src/ReactDebugHooks.js
@@ -18,13 +18,9 @@ import type {
   Fiber,
   Dispatcher as DispatcherType,
 } from 'react-reconciler/src/ReactInternalTypes';
-import type {OpaqueIDType} from 'react-reconciler/src/ReactFiberHostConfig';
-
-import {NoMode} from 'react-reconciler/src/ReactTypeOfMode';
 
 import ErrorStackParser from 'error-stack-parser';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
-import {REACT_OPAQUE_ID_TYPE} from 'shared/ReactSymbols';
 import {
   FunctionComponent,
   SimpleMemoComponent,
@@ -53,8 +49,6 @@ type Dispatch<A> = A => void;
 
 let primitiveStackCache: null | Map<string, Array<any>> = null;
 
-let currentFiber: Fiber | null = null;
-
 type Hook = {
   memoizedState: any,
   next: Hook | null,
@@ -324,23 +318,6 @@ function useDeferredValue<T>(value: T): T {
   return value;
 }
 
-function useOpaqueIdentifier(): OpaqueIDType | void {
-  const hook = nextHook(); // State
-  if (currentFiber && currentFiber.mode === NoMode) {
-    nextHook(); // Effect
-  }
-  let value = hook === null ? undefined : hook.memoizedState;
-  if (value && value.$$typeof === REACT_OPAQUE_ID_TYPE) {
-    value = undefined;
-  }
-  hookLog.push({
-    primitive: 'OpaqueIdentifier',
-    stackError: new Error(),
-    value,
-  });
-  return value;
-}
-
 function useId(): string {
   const hook = nextHook();
   const id = hook !== null ? hook.memoizedState : '';
@@ -371,7 +348,6 @@ const Dispatcher: DispatcherType = {
   useMutableSource,
   useSyncExternalStore,
   useDeferredValue,
-  useOpaqueIdentifier,
   useId,
 };
 
@@ -767,8 +743,6 @@ export function inspectHooksOfFiber(
     currentDispatcher = ReactSharedInternals.ReactCurrentDispatcher;
   }
 
-  currentFiber = fiber;
-
   if (
     fiber.tag !== FunctionComponent &&
     fiber.tag !== SimpleMemoComponent &&
diff --git a/packages/react-debug-tools/src/__tests__/ReactHooksInspectionIntegration-test.js b/packages/react-debug-tools/src/__tests__/ReactHooksInspectionIntegration-test.js
index d17a01a258277..559a0bf75e52f 100644
--- a/packages/react-debug-tools/src/__tests__/ReactHooksInspectionIntegration-test.js
+++ b/packages/react-debug-tools/src/__tests__/ReactHooksInspectionIntegration-test.js
@@ -598,64 +598,6 @@ describe('ReactHooksInspectionIntegration', () => {
     ]);
   });
 
-  it('should support composite useOpaqueIdentifier hook', () => {
-    function Foo(props) {
-      const id = React.unstable_useOpaqueIdentifier();
-      const [state] = React.useState(() => 'hello', []);
-      return <div id={id}>{state}</div>;
-    }
-
-    const renderer = ReactTestRenderer.create(<Foo />);
-    const childFiber = renderer.root.findByType(Foo)._currentFiber();
-    const tree = ReactDebugTools.inspectHooksOfFiber(childFiber);
-
-    expect(tree.length).toEqual(2);
-
-    expect(tree[0].id).toEqual(0);
-    expect(tree[0].isStateEditable).toEqual(false);
-    expect(tree[0].name).toEqual('OpaqueIdentifier');
-    expect(String(tree[0].value).startsWith('c_')).toBe(true);
-
-    expect(tree[1]).toEqual({
-      id: 1,
-      isStateEditable: true,
-      name: 'State',
-      value: 'hello',
-      subHooks: [],
-    });
-  });
-
-  it('should support composite useOpaqueIdentifier hook in concurrent mode', () => {
-    function Foo(props) {
-      const id = React.unstable_useOpaqueIdentifier();
-      const [state] = React.useState('hello');
-      return <div id={id}>{state}</div>;
-    }
-
-    const renderer = ReactTestRenderer.create(<Foo />, {
-      unstable_isConcurrent: true,
-    });
-    expect(Scheduler).toFlushWithoutYielding();
-
-    const childFiber = renderer.root.findByType(Foo)._currentFiber();
-    const tree = ReactDebugTools.inspectHooksOfFiber(childFiber);
-
-    expect(tree.length).toEqual(2);
-
-    expect(tree[0].id).toEqual(0);
-    expect(tree[0].isStateEditable).toEqual(false);
-    expect(tree[0].name).toEqual('OpaqueIdentifier');
-    expect(String(tree[0].value).startsWith('c_')).toBe(true);
-
-    expect(tree[1]).toEqual({
-      id: 1,
-      isStateEditable: true,
-      name: 'State',
-      value: 'hello',
-      subHooks: [],
-    });
-  });
-
   it('should support useId hook', () => {
     function Foo(props) {
       const id = React.unstable_useId();
diff --git a/packages/react-devtools-shared/src/backend/ReactSymbols.js b/packages/react-devtools-shared/src/backend/ReactSymbols.js
index c6515f02edc51..ebc6920be8d2f 100644
--- a/packages/react-devtools-shared/src/backend/ReactSymbols.js
+++ b/packages/react-devtools-shared/src/backend/ReactSymbols.js
@@ -40,9 +40,6 @@ export const LAZY_SYMBOL_STRING = 'Symbol(react.lazy)';
 export const MEMO_NUMBER = 0xead3;
 export const MEMO_SYMBOL_STRING = 'Symbol(react.memo)';
 
-export const OPAQUE_ID_NUMBER = 0xeae0;
-export const OPAQUE_ID_SYMBOL_STRING = 'Symbol(react.opaque.id)';
-
 export const PORTAL_NUMBER = 0xeaca;
 export const PORTAL_SYMBOL_STRING = 'Symbol(react.portal)';
 
diff --git a/packages/react-dom/src/__tests__/ReactDOMServerIntegrationHooks-test.js b/packages/react-dom/src/__tests__/ReactDOMServerIntegrationHooks-test.js
index ba2b22437bc1b..114c522313a79 100644
--- a/packages/react-dom/src/__tests__/ReactDOMServerIntegrationHooks-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMServerIntegrationHooks-test.js
@@ -17,8 +17,6 @@ let React;
 let ReactDOM;
 let ReactDOMServer;
 let ReactTestUtils;
-let act;
-let Scheduler;
 let useState;
 let useReducer;
 let useEffect;
@@ -30,7 +28,6 @@ let useImperativeHandle;
 let useInsertionEffect;
 let useLayoutEffect;
 let useDebugValue;
-let useOpaqueIdentifier;
 let forwardRef;
 let yieldedValues;
 let yieldValue;
@@ -44,8 +41,6 @@ function initModules() {
   ReactDOM = require('react-dom');
   ReactDOMServer = require('react-dom/server');
   ReactTestUtils = require('react-dom/test-utils');
-  Scheduler = require('scheduler');
-  act = require('jest-react').act;
   useState = React.useState;
   useReducer = React.useReducer;
   useEffect = React.useEffect;
@@ -57,7 +52,6 @@ function initModules() {
   useImperativeHandle = React.useImperativeHandle;
   useInsertionEffect = React.useInsertionEffect;
   useLayoutEffect = React.useLayoutEffect;
-  useOpaqueIdentifier = React.unstable_useOpaqueIdentifier;
   forwardRef = React.forwardRef;
 
   yieldedValues = [];
@@ -83,9 +77,6 @@ const {
   itRenders,
   itThrowsWhenRendering,
   serverRender,
-  streamRender,
-  clientCleanRender,
-  clientRenderOnServerString,
 } = ReactDOMServerIntegrationUtils(initModules);
 
 describe('ReactDOMServerHooks', () => {
@@ -910,1104 +901,4 @@ describe('ReactDOMServerHooks', () => {
     );
     expect(container.children[0].textContent).toEqual('0');
   });
-
-  describe('useOpaqueIdentifier', () => {
-    it('generates unique ids for server string render', async () => {
-      function App(props) {
-        const idOne = useOpaqueIdentifier();
-        const idTwo = useOpaqueIdentifier();
-        return (
-          <div>
-            <div aria-labelledby={idOne} />
-            <div id={idOne} />
-            <span aria-labelledby={idTwo} />
-            <span id={idTwo} />
-          </div>
-        );
-      }
-
-      const domNode = await serverRender(<App />);
-      expect(domNode.children.length).toEqual(4);
-      expect(domNode.children[0].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[1].getAttribute('id'),
-      );
-      expect(domNode.children[2].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[3].getAttribute('id'),
-      );
-      expect(domNode.children[0].getAttribute('aria-labelledby')).not.toEqual(
-        domNode.children[2].getAttribute('aria-labelledby'),
-      );
-      expect(
-        domNode.children[0].getAttribute('aria-labelledby'),
-      ).not.toBeNull();
-      expect(
-        domNode.children[2].getAttribute('aria-labelledby'),
-      ).not.toBeNull();
-    });
-
-    it('generates unique ids for server stream render', async () => {
-      function App(props) {
-        const idOne = useOpaqueIdentifier();
-        const idTwo = useOpaqueIdentifier();
-        return (
-          <div>
-            <div aria-labelledby={idOne} />
-            <div id={idOne} />
-            <span aria-labelledby={idTwo} />
-            <span id={idTwo} />
-          </div>
-        );
-      }
-
-      const domNode = await streamRender(<App />);
-      expect(domNode.children.length).toEqual(4);
-      expect(domNode.children[0].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[1].getAttribute('id'),
-      );
-      expect(domNode.children[2].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[3].getAttribute('id'),
-      );
-      expect(domNode.children[0].getAttribute('aria-labelledby')).not.toEqual(
-        domNode.children[2].getAttribute('aria-labelledby'),
-      );
-      expect(
-        domNode.children[0].getAttribute('aria-labelledby'),
-      ).not.toBeNull();
-      expect(
-        domNode.children[2].getAttribute('aria-labelledby'),
-      ).not.toBeNull();
-    });
-
-    it('generates unique ids for client render', async () => {
-      function App(props) {
-        const idOne = useOpaqueIdentifier();
-        const idTwo = useOpaqueIdentifier();
-        return (
-          <div>
-            <div aria-labelledby={idOne} />
-            <div id={idOne} />
-            <span aria-labelledby={idTwo} />
-            <span id={idTwo} />
-          </div>
-        );
-      }
-
-      const domNode = await clientCleanRender(<App />);
-      expect(domNode.children.length).toEqual(4);
-      expect(domNode.children[0].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[1].getAttribute('id'),
-      );
-      expect(domNode.children[2].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[3].getAttribute('id'),
-      );
-      expect(domNode.children[0].getAttribute('aria-labelledby')).not.toEqual(
-        domNode.children[2].getAttribute('aria-labelledby'),
-      );
-      expect(
-        domNode.children[0].getAttribute('aria-labelledby'),
-      ).not.toBeNull();
-      expect(
-        domNode.children[2].getAttribute('aria-labelledby'),
-      ).not.toBeNull();
-    });
-
-    it('generates unique ids for client render on good server markup', async () => {
-      function App(props) {
-        const idOne = useOpaqueIdentifier();
-        const idTwo = useOpaqueIdentifier();
-        return (
-          <div>
-            <div aria-labelledby={idOne} />
-            <div id={idOne} />
-            <span aria-labelledby={idTwo} />
-            <span id={idTwo} />
-          </div>
-        );
-      }
-
-      const domNode = await clientRenderOnServerString(<App />);
-      expect(domNode.children.length).toEqual(4);
-      expect(domNode.children[0].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[1].getAttribute('id'),
-      );
-      expect(domNode.children[2].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[3].getAttribute('id'),
-      );
-      expect(domNode.children[0].getAttribute('aria-labelledby')).not.toEqual(
-        domNode.children[2].getAttribute('aria-labelledby'),
-      );
-      expect(
-        domNode.children[0].getAttribute('aria-labelledby'),
-      ).not.toBeNull();
-      expect(
-        domNode.children[2].getAttribute('aria-labelledby'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier does not change id even if the component updates during client render', async () => {
-      let _setShowId;
-      function App() {
-        const id = useOpaqueIdentifier();
-        const [showId, setShowId] = useState(false);
-        _setShowId = setShowId;
-        return (
-          <div>
-            <div aria-labelledby={id} />
-            {showId && <div id={id} />}
-          </div>
-        );
-      }
-
-      const domNode = await clientCleanRender(<App />);
-      const oldClientId = domNode.children[0].getAttribute('aria-labelledby');
-
-      expect(domNode.children.length).toEqual(1);
-      expect(oldClientId).not.toBeNull();
-
-      await act(async () => _setShowId(true));
-
-      expect(domNode.children.length).toEqual(2);
-      expect(domNode.children[0].getAttribute('aria-labelledby')).toEqual(
-        domNode.children[1].getAttribute('id'),
-      );
-      expect(domNode.children[0].getAttribute('aria-labelledby')).toEqual(
-        oldClientId,
-      );
-    });
-
-    it('useOpaqueIdentifier identifierPrefix works for server renderer and does not clash', async () => {
-      function ChildTwo({id}) {
-        return <div id={id}>Child Three</div>;
-      }
-      function App() {
-        const id = useOpaqueIdentifier();
-        const idTwo = useOpaqueIdentifier();
-
-        return (
-          <div>
-            <div aria-labelledby={id}>Child One</div>
-            <ChildTwo id={id} />
-            <div aria-labelledby={idTwo}>Child Three</div>
-            <div id={idTwo}>Child Four</div>
-          </div>
-        );
-      }
-
-      const containerOne = document.createElement('div');
-      document.body.append(containerOne);
-
-      containerOne.innerHTML = ReactDOMServer.renderToString(<App />, {
-        identifierPrefix: 'one',
-      });
-
-      const containerTwo = document.createElement('div');
-      document.body.append(containerTwo);
-
-      containerTwo.innerHTML = ReactDOMServer.renderToString(<App />, {
-        identifierPrefix: 'two',
-      });
-
-      expect(document.body.children.length).toEqual(2);
-      const childOne = document.body.children[0];
-      const childTwo = document.body.children[1];
-
-      expect(
-        childOne.children[0].children[0].getAttribute('aria-labelledby'),
-      ).toEqual(childOne.children[0].children[1].getAttribute('id'));
-      expect(
-        childOne.children[0].children[2].getAttribute('aria-labelledby'),
-      ).toEqual(childOne.children[0].children[3].getAttribute('id'));
-
-      expect(
-        childOne.children[0].children[0].getAttribute('aria-labelledby'),
-      ).not.toEqual(
-        childOne.children[0].children[2].getAttribute('aria-labelledby'),
-      );
-
-      expect(
-        childOne.children[0].children[0]
-          .getAttribute('aria-labelledby')
-          .startsWith('one'),
-      ).toBe(true);
-      expect(
-        childOne.children[0].children[2]
-          .getAttribute('aria-labelledby')
-          .includes('one'),
-      ).toBe(true);
-
-      expect(
-        childTwo.children[0].children[0].getAttribute('aria-labelledby'),
-      ).toEqual(childTwo.children[0].children[1].getAttribute('id'));
-      expect(
-        childTwo.children[0].children[2].getAttribute('aria-labelledby'),
-      ).toEqual(childTwo.children[0].children[3].getAttribute('id'));
-
-      expect(
-        childTwo.children[0].children[0].getAttribute('aria-labelledby'),
-      ).not.toEqual(
-        childTwo.children[0].children[2].getAttribute('aria-labelledby'),
-      );
-
-      expect(
-        childTwo.children[0].children[0]
-          .getAttribute('aria-labelledby')
-          .startsWith('two'),
-      ).toBe(true);
-      expect(
-        childTwo.children[0].children[2]
-          .getAttribute('aria-labelledby')
-          .startsWith('two'),
-      ).toBe(true);
-    });
-
-    it('useOpaqueIdentifier identifierPrefix works for multiple reads on a streaming server renderer', async () => {
-      function ChildTwo() {
-        const id = useOpaqueIdentifier();
-
-        return <div id={id}>Child Two</div>;
-      }
-
-      function App() {
-        const id = useOpaqueIdentifier();
-
-        return (
-          <>
-            <div id={id}>Child One</div>
-            <ChildTwo />
-            <div aria-labelledby={id}>Aria One</div>
-          </>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.append(container);
-
-      const streamOne = ReactDOMServer.renderToNodeStream(<App />, {
-        identifierPrefix: 'one',
-      }).setEncoding('utf8');
-      const streamTwo = ReactDOMServer.renderToNodeStream(<App />, {
-        identifierPrefix: 'two',
-      }).setEncoding('utf8');
-
-      const streamOneIsDone = new Promise((resolve, reject) => {
-        streamOne.on('end', () => resolve());
-        streamOne.on('error', e => reject(e));
-      });
-      const streamTwoIsDone = new Promise((resolve, reject) => {
-        streamTwo.on('end', () => resolve());
-        streamTwo.on('error', e => reject(e));
-      });
-
-      const containerOne = document.createElement('div');
-      const containerTwo = document.createElement('div');
-
-      streamOne._read(10);
-      streamTwo._read(10);
-
-      containerOne.innerHTML = streamOne.read();
-      containerTwo.innerHTML = streamTwo.read();
-
-      expect(containerOne.children[0].getAttribute('id')).not.toEqual(
-        containerOne.children[1].getAttribute('id'),
-      );
-      expect(containerTwo.children[0].getAttribute('id')).not.toEqual(
-        containerTwo.children[1].getAttribute('id'),
-      );
-      expect(containerOne.children[0].getAttribute('id')).not.toEqual(
-        containerTwo.children[0].getAttribute('id'),
-      );
-      expect(containerOne.children[0].getAttribute('id').includes('one')).toBe(
-        true,
-      );
-      expect(containerOne.children[1].getAttribute('id').includes('one')).toBe(
-        true,
-      );
-      expect(containerTwo.children[0].getAttribute('id').includes('two')).toBe(
-        true,
-      );
-      expect(containerTwo.children[1].getAttribute('id').includes('two')).toBe(
-        true,
-      );
-
-      expect(containerOne.children[1].getAttribute('id')).not.toEqual(
-        containerTwo.children[1].getAttribute('id'),
-      );
-      expect(containerOne.children[0].getAttribute('id')).toEqual(
-        containerOne.children[2].getAttribute('aria-labelledby'),
-      );
-      expect(containerTwo.children[0].getAttribute('id')).toEqual(
-        containerTwo.children[2].getAttribute('aria-labelledby'),
-      );
-
-      // Exhaust the rest of the stream
-      class Sink extends require('stream').Writable {
-        _write(chunk, encoding, done) {
-          done();
-        }
-      }
-      streamOne.pipe(new Sink());
-      streamTwo.pipe(new Sink());
-
-      await Promise.all([streamOneIsDone, streamTwoIsDone]);
-    });
-
-    it('useOpaqueIdentifier: IDs match when, after hydration, a new component that uses the ID is rendered', async () => {
-      let _setShowDiv;
-      function App() {
-        const id = useOpaqueIdentifier();
-        const [showDiv, setShowDiv] = useState(false);
-        _setShowDiv = setShowDiv;
-
-        return (
-          <div>
-            <div id={id}>Child One</div>
-            {showDiv && <div id={id}>Child Two</div>}
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.append(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-      const root = ReactDOM.createRoot(container, {hydrate: true});
-      root.render(<App />);
-      Scheduler.unstable_flushAll();
-      jest.runAllTimers();
-
-      expect(container.children[0].children.length).toEqual(1);
-      const oldServerId = container.children[0].children[0].getAttribute('id');
-      expect(oldServerId).not.toBeNull();
-
-      await act(async () => {
-        _setShowDiv(true);
-      });
-      expect(container.children[0].children.length).toEqual(2);
-      expect(container.children[0].children[0].getAttribute('id')).toEqual(
-        container.children[0].children[1].getAttribute('id'),
-      );
-      expect(container.children[0].children[0].getAttribute('id')).not.toEqual(
-        oldServerId,
-      );
-      expect(
-        container.children[0].children[0].getAttribute('id'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier: IDs match when, after hydration, a new component that uses the ID is rendered for legacy', async () => {
-      let _setShowDiv;
-      function App() {
-        const id = useOpaqueIdentifier();
-        const [showDiv, setShowDiv] = useState(false);
-        _setShowDiv = setShowDiv;
-
-        return (
-          <div>
-            <div id={id}>Child One</div>
-            {showDiv && <div id={id}>Child Two</div>}
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.append(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-      ReactDOM.hydrate(<App />, container);
-
-      expect(container.children[0].children.length).toEqual(1);
-      const oldServerId = container.children[0].children[0].getAttribute('id');
-      expect(oldServerId).not.toBeNull();
-
-      await act(async () => {
-        _setShowDiv(true);
-      });
-      expect(container.children[0].children.length).toEqual(2);
-      expect(container.children[0].children[0].getAttribute('id')).toEqual(
-        container.children[0].children[1].getAttribute('id'),
-      );
-      expect(container.children[0].children[0].getAttribute('id')).not.toEqual(
-        oldServerId,
-      );
-      expect(
-        container.children[0].children[0].getAttribute('id'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier: ID is not used during hydration but is used in an update', async () => {
-      let _setShow;
-      function App({unused}) {
-        Scheduler.unstable_yieldValue('App');
-        const id = useOpaqueIdentifier();
-        const [show, setShow] = useState(false);
-        _setShow = setShow;
-        return (
-          <div>
-            <span id={show ? id : null}>{'Child One'}</span>
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.append(container);
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-      const root = ReactDOM.createRoot(container, {hydrate: true});
-      act(() => {
-        root.render(<App />);
-      });
-      expect(Scheduler).toHaveYielded(['App', 'App']);
-      // The ID goes from not being used to being added to the page
-      act(() => {
-        _setShow(true);
-      });
-      expect(Scheduler).toHaveYielded(['App', 'App']);
-      expect(
-        container.getElementsByTagName('span')[0].getAttribute('id'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier: ID is not used during hydration but is used in an update in legacy', async () => {
-      let _setShow;
-      function App({unused}) {
-        Scheduler.unstable_yieldValue('App');
-        const id = useOpaqueIdentifier();
-        const [show, setShow] = useState(false);
-        _setShow = setShow;
-        return (
-          <div>
-            <span id={show ? id : null}>{'Child One'}</span>
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.append(container);
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-      ReactDOM.hydrate(<App />, container);
-      expect(Scheduler).toHaveYielded(['App', 'App']);
-      // The ID goes from not being used to being added to the page
-      act(() => {
-        _setShow(true);
-      });
-      expect(Scheduler).toHaveYielded(['App']);
-      expect(
-        container.getElementsByTagName('span')[0].getAttribute('id'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier: flushSync', async () => {
-      let _setShow;
-      function App() {
-        const id = useOpaqueIdentifier();
-        const [show, setShow] = useState(false);
-        _setShow = setShow;
-        return (
-          <div>
-            <span id={show ? id : null}>{'Child One'}</span>
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.append(container);
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-      const root = ReactDOM.createRoot(container, {hydrate: true});
-      act(() => {
-        root.render(<App />);
-      });
-
-      // The ID goes from not being used to being added to the page
-      act(() => {
-        ReactDOM.flushSync(() => {
-          _setShow(true);
-        });
-      });
-      expect(
-        container.getElementsByTagName('span')[0].getAttribute('id'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier: children with id hydrates before other children if ID updates', async () => {
-      let _setShow;
-
-      const child1Ref = React.createRef();
-      const childWithIDRef = React.createRef();
-      const setShowRef = React.createRef();
-
-      // RENAME THESE
-      function Child1() {
-        Scheduler.unstable_yieldValue('Child One');
-        return <span ref={child1Ref}>{'Child One'}</span>;
-      }
-
-      function Child2() {
-        Scheduler.unstable_yieldValue('Child Two');
-        return <span>{'Child Two'}</span>;
-      }
-
-      const Children = React.memo(function Children() {
-        return (
-          <React.Suspense fallback="Loading 1...">
-            <Child1 />
-            <Child2 />
-          </React.Suspense>
-        );
-      });
-
-      function ChildWithID({parentID}) {
-        Scheduler.unstable_yieldValue('Child with ID');
-        return (
-          <span id={parentID} ref={childWithIDRef}>
-            {'Child with ID'}
-          </span>
-        );
-      }
-
-      const ChildrenWithID = React.memo(function ChildrenWithID({parentID}) {
-        return (
-          <React.Suspense fallback="Loading 2...">
-            <ChildWithID parentID={parentID} />
-          </React.Suspense>
-        );
-      });
-
-      function App() {
-        const id = useOpaqueIdentifier();
-        const [show, setShow] = useState(false);
-        _setShow = setShow;
-        return (
-          <div>
-            <Children />
-            <ChildrenWithID parentID={id} />
-            {show && (
-              <span aria-labelledby={id} ref={setShowRef}>
-                {'Child Three'}
-              </span>
-            )}
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-      expect(Scheduler).toHaveYielded([
-        'Child One',
-        'Child Two',
-        'Child with ID',
-      ]);
-      expect(container.textContent).toEqual('Child OneChild TwoChild with ID');
-
-      const serverId = container
-        .getElementsByTagName('span')[2]
-        .getAttribute('id');
-      expect(serverId).not.toBeNull();
-
-      const root = ReactDOM.createRoot(container, {hydrate: true});
-      root.render(<App show={false} />);
-      expect(Scheduler).toHaveYielded([]);
-
-      //Hydrate just child one before updating state
-      expect(Scheduler).toFlushAndYieldThrough(['Child One']);
-      expect(child1Ref.current).toBe(null);
-      expect(Scheduler).toHaveYielded([]);
-
-      act(() => {
-        _setShow(true);
-
-        // State update should trigger the ID to update, which changes the props
-        // of ChildWithID. This should cause ChildWithID to hydrate before Children
-
-        expect(Scheduler).toFlushAndYieldThrough([
-          'Child with ID',
-          // Fallbacks are immediately committed in TestUtils version
-          // of act
-          // 'Child with ID',
-          // 'Child with ID',
-          'Child One',
-          'Child Two',
-        ]);
-
-        expect(child1Ref.current).toBe(null);
-        expect(childWithIDRef.current).toEqual(
-          container.getElementsByTagName('span')[2],
-        );
-
-        expect(setShowRef.current).toEqual(
-          container.getElementsByTagName('span')[3],
-        );
-
-        expect(childWithIDRef.current.getAttribute('id')).toEqual(
-          setShowRef.current.getAttribute('aria-labelledby'),
-        );
-        expect(childWithIDRef.current.getAttribute('id')).not.toEqual(serverId);
-      });
-
-      // Children hydrates after ChildWithID
-      expect(child1Ref.current).toBe(container.getElementsByTagName('span')[0]);
-
-      Scheduler.unstable_flushAll();
-
-      expect(Scheduler).toHaveYielded([]);
-    });
-
-    it('useOpaqueIdentifier: IDs match when part of the DOM tree is server rendered and part is client rendered', async () => {
-      let suspend = true;
-      let resolve;
-      const promise = new Promise(resolvePromise => (resolve = resolvePromise));
-
-      function Child({text}) {
-        if (suspend) {
-          throw promise;
-        } else {
-          return text;
-        }
-      }
-
-      function RenderedChild() {
-        useEffect(() => {
-          Scheduler.unstable_yieldValue('Child did commit');
-        });
-        return null;
-      }
-
-      function App() {
-        const id = useOpaqueIdentifier();
-        useEffect(() => {
-          Scheduler.unstable_yieldValue('Did commit');
-        });
-        return (
-          <div>
-            <div id={id}>Child One</div>
-            <RenderedChild />
-            <React.Suspense fallback={'Fallback'}>
-              <div id={id}>
-                <Child text="Child Two" />
-              </div>
-            </React.Suspense>
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-
-      suspend = true;
-      const root = ReactDOM.createRoot(container, {hydrate: true});
-      await act(async () => {
-        root.render(<App />);
-      });
-      jest.runAllTimers();
-      expect(Scheduler).toHaveYielded(['Child did commit', 'Did commit']);
-      expect(Scheduler).toFlushAndYield([]);
-
-      const serverId = container.children[0].children[0].getAttribute('id');
-      expect(container.children[0].children.length).toEqual(1);
-      expect(
-        container.children[0].children[0].getAttribute('id'),
-      ).not.toBeNull();
-
-      await act(async () => {
-        suspend = false;
-        resolve();
-        await promise;
-      });
-
-      expect(Scheduler).toHaveYielded(['Child did commit', 'Did commit']);
-      expect(Scheduler).toFlushAndYield([]);
-      jest.runAllTimers();
-
-      expect(container.children[0].children.length).toEqual(2);
-      expect(container.children[0].children[0].getAttribute('id')).toEqual(
-        container.children[0].children[1].getAttribute('id'),
-      );
-      expect(container.children[0].children[0].getAttribute('id')).not.toEqual(
-        serverId,
-      );
-      expect(
-        container.children[0].children[0].getAttribute('id'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier warn when there is a hydration error', async () => {
-      function Child({appId}) {
-        return <div aria-labelledby={appId} />;
-      }
-      function App() {
-        const id = useOpaqueIdentifier();
-        return <Child appId={id} />;
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      // This is the wrong HTML string
-      container.innerHTML = '<span></span>';
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-      expect(() => Scheduler.unstable_flushAll()).toErrorDev(
-        [
-          'Warning: An error occurred during hydration. The server HTML was replaced with client content in <div>.',
-          'Warning: Expected server HTML to contain a matching <div> in <div>.',
-        ],
-        {withoutStack: 1},
-      );
-    });
-
-    it('useOpaqueIdentifier: IDs match when part of the DOM tree is server rendered and part is client rendered', async () => {
-      let suspend = true;
-
-      function Child({text}) {
-        if (suspend) {
-          throw new Promise(() => {});
-        } else {
-          return text;
-        }
-      }
-
-      function RenderedChild() {
-        useEffect(() => {
-          Scheduler.unstable_yieldValue('Child did commit');
-        });
-        return null;
-      }
-
-      function App() {
-        const id = useOpaqueIdentifier();
-        useEffect(() => {
-          Scheduler.unstable_yieldValue('Did commit');
-        });
-        return (
-          <div>
-            <div id={id}>Child One</div>
-            <RenderedChild />
-            <React.Suspense fallback={'Fallback'}>
-              <div id={id}>
-                <Child text="Child Two" />
-              </div>
-            </React.Suspense>
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-
-      suspend = false;
-      const root = ReactDOM.createRoot(container, {hydrate: true});
-      await act(async () => {
-        root.render(<App />);
-      });
-      jest.runAllTimers();
-      expect(Scheduler).toHaveYielded([
-        'Child did commit',
-        'Did commit',
-        'Child did commit',
-        'Did commit',
-      ]);
-      expect(Scheduler).toFlushAndYield([]);
-
-      expect(container.children[0].children.length).toEqual(2);
-      expect(container.children[0].children[0].getAttribute('id')).toEqual(
-        container.children[0].children[1].getAttribute('id'),
-      );
-      expect(
-        container.children[0].children[0].getAttribute('id'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier warn when there is a hydration error', async () => {
-      function Child({appId}) {
-        return <div aria-labelledby={appId} />;
-      }
-      function App() {
-        const id = useOpaqueIdentifier();
-        return <Child appId={id} />;
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      // This is the wrong HTML string
-      container.innerHTML = '<span></span>';
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-      expect(() => Scheduler.unstable_flushAll()).toErrorDev(
-        [
-          'Warning: An error occurred during hydration. The server HTML was replaced with client content in <div>.',
-          'Warning: Expected server HTML to contain a matching <div> in <div>.',
-        ],
-        {withoutStack: 1},
-      );
-    });
-
-    it('useOpaqueIdentifier warns when there is a hydration error and we are using ID as a string', async () => {
-      function Child({appId}) {
-        return <div aria-labelledby={String(appId)} />;
-      }
-      function App() {
-        const id = useOpaqueIdentifier();
-        return <Child appId={id} />;
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      // This is the wrong HTML string
-      container.innerHTML = '<span></span>';
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-      expect(() => Scheduler.unstable_flushAll()).toErrorDev(
-        [
-          'Warning: The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. Do not read the value directly.',
-          'Warning: An error occurred during hydration. The server HTML was replaced with client content in <div>.',
-        ],
-        {withoutStack: 1},
-      );
-    });
-
-    it('useOpaqueIdentifier warns when there is a hydration error and we are using ID as a string', async () => {
-      function Child({appId}) {
-        return <div aria-labelledby={String(appId)} />;
-      }
-      function App() {
-        const id = useOpaqueIdentifier();
-        return <Child appId={id} />;
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      // This is the wrong HTML string
-      container.innerHTML = '<span></span>';
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-      expect(() => Scheduler.unstable_flushAll()).toErrorDev(
-        [
-          'Warning: The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. Do not read the value directly.',
-          'Warning: An error occurred during hydration. The server HTML was replaced with client content in <div>.',
-        ],
-        {withoutStack: 1},
-      );
-    });
-
-    it('useOpaqueIdentifier warns if you try to use the result as a string in a child component', async () => {
-      function Child({appId}) {
-        return <div aria-labelledby={String(appId)} />;
-      }
-      function App() {
-        const id = useOpaqueIdentifier();
-        return <Child appId={id} />;
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-      expect(() => Scheduler.unstable_flushAll()).toErrorDev(
-        [
-          'Warning: The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. Do not read the value directly.',
-          'Warning: An error occurred during hydration. The server HTML was replaced with client content in <div>.',
-        ],
-        {withoutStack: 1},
-      );
-    });
-
-    it('useOpaqueIdentifier warns if you try to use the result as a string', async () => {
-      function App() {
-        const id = useOpaqueIdentifier();
-        return <div aria-labelledby={String(id)} />;
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-      expect(() => Scheduler.unstable_flushAll()).toErrorDev(
-        [
-          'Warning: The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. Do not read the value directly.',
-          'Warning: An error occurred during hydration. The server HTML was replaced with client content in <div>.',
-        ],
-        {withoutStack: 1},
-      );
-    });
-
-    it('useOpaqueIdentifier warns if you try to use the result as a string in a child component wrapped in a Suspense', async () => {
-      function Child({appId}) {
-        return <div aria-labelledby={String(appId)} />;
-      }
-      function App() {
-        const id = useOpaqueIdentifier();
-        return (
-          <React.Suspense fallback={null}>
-            <Child appId={id} />
-          </React.Suspense>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-
-      if (gate(flags => flags.deferRenderPhaseUpdateToNextBatch)) {
-        expect(() => Scheduler.unstable_flushAll()).toErrorDev([
-          'The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. ' +
-            'Do not read the value directly.',
-        ]);
-      } else {
-        // This error isn't surfaced to the user; only the warning is.
-        // The error is just the mechanism that restarts the render.
-        expect(() =>
-          expect(() => Scheduler.unstable_flushAll()).toThrow(
-            'The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. ' +
-              'Do not read the value directly.',
-          ),
-        ).toErrorDev([
-          'The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. ' +
-            'Do not read the value directly.',
-        ]);
-      }
-    });
-
-    it('useOpaqueIdentifier warns if you try to add the result as a number in a child component wrapped in a Suspense', async () => {
-      function Child({appId}) {
-        return <div aria-labelledby={+appId} />;
-      }
-      function App() {
-        const [show] = useState(false);
-        const id = useOpaqueIdentifier();
-        return (
-          <React.Suspense fallback={null}>
-            {show && <div id={id} />}
-            <Child appId={id} />
-          </React.Suspense>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-
-      if (gate(flags => flags.deferRenderPhaseUpdateToNextBatch)) {
-        expect(() => Scheduler.unstable_flushAll()).toErrorDev([
-          'The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. ' +
-            'Do not read the value directly.',
-        ]);
-      } else {
-        // This error isn't surfaced to the user; only the warning is.
-        // The error is just the mechanism that restarts the render.
-        expect(() =>
-          expect(() => Scheduler.unstable_flushAll()).toThrow(
-            'The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. ' +
-              'Do not read the value directly.',
-          ),
-        ).toErrorDev([
-          'The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. ' +
-            'Do not read the value directly.',
-        ]);
-      }
-    });
-
-    it('useOpaqueIdentifier with two opaque identifiers on the same page', () => {
-      let _setShow;
-
-      function App() {
-        const id1 = useOpaqueIdentifier();
-        const id2 = useOpaqueIdentifier();
-        const [show, setShow] = useState(true);
-        _setShow = setShow;
-
-        return (
-          <div>
-            <React.Suspense fallback={null}>
-              {show ? (
-                <span id={id1}>{'Child'}</span>
-              ) : (
-                <span id={id2}>{'Child'}</span>
-              )}
-            </React.Suspense>
-            <span aria-labelledby={id1}>{'test'}</span>
-          </div>
-        );
-      }
-
-      const container = document.createElement('div');
-      document.body.appendChild(container);
-
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-
-      const serverID = container
-        .getElementsByTagName('span')[0]
-        .getAttribute('id');
-      expect(serverID).not.toBeNull();
-      expect(
-        container
-          .getElementsByTagName('span')[1]
-          .getAttribute('aria-labelledby'),
-      ).toEqual(serverID);
-
-      ReactDOM.createRoot(container, {hydrate: true}).render(<App />);
-      jest.runAllTimers();
-      expect(Scheduler).toHaveYielded([]);
-      expect(Scheduler).toFlushAndYield([]);
-
-      act(() => {
-        _setShow(false);
-      });
-
-      expect(
-        container
-          .getElementsByTagName('span')[1]
-          .getAttribute('aria-labelledby'),
-      ).toEqual(serverID);
-      expect(
-        container.getElementsByTagName('span')[0].getAttribute('id'),
-      ).not.toEqual(serverID);
-      expect(
-        container.getElementsByTagName('span')[0].getAttribute('id'),
-      ).not.toBeNull();
-    });
-
-    it('useOpaqueIdentifier with multiple ids in nested components', async () => {
-      function DivWithId({id, children}) {
-        return <div id={id}>{children}</div>;
-      }
-
-      let setShowMore;
-      function App() {
-        const outerId = useOpaqueIdentifier();
-        const innerId = useOpaqueIdentifier();
-        const [showMore, _setShowMore] = useState(false);
-        setShowMore = _setShowMore;
-        return showMore ? (
-          <DivWithId id={outerId}>
-            <DivWithId id={innerId} />
-          </DivWithId>
-        ) : null;
-      }
-
-      const container = document.createElement('div');
-      container.innerHTML = ReactDOMServer.renderToString(<App />);
-
-      await act(async () => {
-        ReactDOM.hydrateRoot(container, <App />);
-      });
-
-      // Show additional content that wasn't part of the initial server-
-      // rendered repsonse.
-      await act(async () => {
-        setShowMore(true);
-      });
-      const [div1, div2] = container.getElementsByTagName('div');
-      expect(typeof div1.getAttribute('id')).toBe('string');
-      expect(typeof div2.getAttribute('id')).toBe('string');
-    });
-  });
 });
diff --git a/packages/react-dom/src/client/DOMPropertyOperations.js b/packages/react-dom/src/client/DOMPropertyOperations.js
index 30fed05aed609..ad94f7ccb7026 100644
--- a/packages/react-dom/src/client/DOMPropertyOperations.js
+++ b/packages/react-dom/src/client/DOMPropertyOperations.js
@@ -21,7 +21,6 @@ import {
   enableTrustedTypesIntegration,
 } from 'shared/ReactFeatureFlags';
 import {checkAttributeStringCoercion} from 'shared/CheckStringCoercion';
-import {isOpaqueHydratingObject} from './ReactDOMHostConfig';
 
 import type {PropertyInfo} from '../shared/DOMProperty';
 
@@ -119,13 +118,6 @@ export function getValueForAttribute(
     if (!isAttributeNameSafe(name)) {
       return;
     }
-
-    // If the object is an opaque reference ID, it's expected that
-    // the next prop is different than the server value, so just return
-    // expected
-    if (isOpaqueHydratingObject(expected)) {
-      return expected;
-    }
     if (!node.hasAttribute(name)) {
       return expected === undefined ? undefined : null;
     }
diff --git a/packages/react-dom/src/client/ReactDOMComponent.js b/packages/react-dom/src/client/ReactDOMComponent.js
index 2d347639eba45..aa9b0281e2f8d 100644
--- a/packages/react-dom/src/client/ReactDOMComponent.js
+++ b/packages/react-dom/src/client/ReactDOMComponent.js
@@ -68,7 +68,6 @@ import possibleStandardNames from '../shared/possibleStandardNames';
 import {validateProperties as validateARIAProperties} from '../shared/ReactDOMInvalidARIAHook';
 import {validateProperties as validateInputProperties} from '../shared/ReactDOMNullInputValuePropHook';
 import {validateProperties as validateUnknownProperties} from '../shared/ReactDOMUnknownPropertyHook';
-import {REACT_OPAQUE_ID_TYPE} from 'shared/ReactSymbols';
 
 import {enableTrustedTypesIntegration} from 'shared/ReactFeatureFlags';
 import {
@@ -775,15 +774,6 @@ export function diffProperties(
         // to update this element.
         updatePayload = [];
       }
-    } else if (
-      typeof nextProp === 'object' &&
-      nextProp !== null &&
-      nextProp.$$typeof === REACT_OPAQUE_ID_TYPE
-    ) {
-      // If we encounter useOpaqueReference's opaque object, this means we are hydrating.
-      // In this case, call the opaque object's toString function which generates a new client
-      // ID so client and server IDs match and throws to rerender.
-      nextProp.toString();
     } else {
       // For any other property we always add it to the queue and then we
       // filter it out using the allowed property list during the commit.
diff --git a/packages/react-dom/src/client/ReactDOMHostConfig.js b/packages/react-dom/src/client/ReactDOMHostConfig.js
index 8a5417ae49272..64fd789b7a1e8 100644
--- a/packages/react-dom/src/client/ReactDOMHostConfig.js
+++ b/packages/react-dom/src/client/ReactDOMHostConfig.js
@@ -59,7 +59,6 @@ import {
 } from '../shared/HTMLNodeType';
 import dangerousStyleValue from '../shared/dangerousStyleValue';
 
-import {REACT_OPAQUE_ID_TYPE} from 'shared/ReactSymbols';
 import {retryIfBlockedOn} from '../events/ReactDOMEventReplaying';
 
 import {
@@ -124,13 +123,6 @@ export type TimeoutHandle = TimeoutID;
 export type NoTimeout = -1;
 export type RendererInspectionConfig = $ReadOnly<{||}>;
 
-export opaque type OpaqueIDType =
-  | string
-  | {
-      toString: () => string | void,
-      valueOf: () => string | void,
-    };
-
 type SelectionInformation = {|
   focusedElem: null | HTMLElement,
   selectionRange: mixed,
@@ -1089,43 +1081,6 @@ export function getInstanceFromNode(node: HTMLElement): null | Object {
   return getClosestInstanceFromNode(node) || null;
 }
 
-let clientId: number = 0;
-export function makeClientId(): OpaqueIDType {
-  return 'r:' + (clientId++).toString(36);
-}
-
-export function makeClientIdInDEV(warnOnAccessInDEV: () => void): OpaqueIDType {
-  const id = 'r:' + (clientId++).toString(36);
-  return {
-    toString() {
-      warnOnAccessInDEV();
-      return id;
-    },
-    valueOf() {
-      warnOnAccessInDEV();
-      return id;
-    },
-  };
-}
-
-export function isOpaqueHydratingObject(value: mixed): boolean {
-  return (
-    value !== null &&
-    typeof value === 'object' &&
-    value.$$typeof === REACT_OPAQUE_ID_TYPE
-  );
-}
-
-export function makeOpaqueHydratingObject(
-  attemptToReadValue: () => void,
-): OpaqueIDType {
-  return {
-    $$typeof: REACT_OPAQUE_ID_TYPE,
-    toString: attemptToReadValue,
-    valueOf: attemptToReadValue,
-  };
-}
-
 export function preparePortalMount(portalInstance: Instance): void {
   listenToAllSupportedEvents(portalInstance);
 }
diff --git a/packages/react-dom/src/server/ReactDOMServerFormatConfig.js b/packages/react-dom/src/server/ReactDOMServerFormatConfig.js
index 2012392004e52..65a10974b0196 100644
--- a/packages/react-dom/src/server/ReactDOMServerFormatConfig.js
+++ b/packages/react-dom/src/server/ReactDOMServerFormatConfig.js
@@ -64,9 +64,7 @@ export type ResponseState = {
   placeholderPrefix: PrecomputedChunk,
   segmentPrefix: PrecomputedChunk,
   boundaryPrefix: string,
-  opaqueIdentifierPrefix: string,
   nextSuspenseID: number,
-  nextOpaqueID: number,
   sentCompleteSegmentFunction: boolean,
   sentCompleteBoundaryFunction: boolean,
   sentClientRenderFunction: boolean, // We allow the legacy renderer to extend this object.
@@ -127,9 +125,7 @@ export function createResponseState(
     placeholderPrefix: stringToPrecomputedChunk(idPrefix + 'P:'),
     segmentPrefix: stringToPrecomputedChunk(idPrefix + 'S:'),
     boundaryPrefix: idPrefix + 'B:',
-    opaqueIdentifierPrefix: idPrefix + 'R:',
     nextSuspenseID: 0,
-    nextOpaqueID: 0,
     sentCompleteSegmentFunction: false,
     sentCompleteBoundaryFunction: false,
     sentClientRenderFunction: false,
@@ -233,24 +229,6 @@ export function assignSuspenseBoundaryID(
   );
 }
 
-export type OpaqueIDType = string;
-
-export function makeServerID(
-  responseState: null | ResponseState,
-): OpaqueIDType {
-  if (responseState === null) {
-    throw new Error(
-      'Invalid hook call. Hooks can only be called inside of the body of a function component.',
-    );
-  }
-
-  // TODO: This is not deterministic since it's created during render.
-  return (
-    responseState.opaqueIdentifierPrefix +
-    (responseState.nextOpaqueID++).toString(36)
-  );
-}
-
 function encodeHTMLTextNode(text: string): string {
   return escapeTextForBrowser(text);
 }
diff --git a/packages/react-dom/src/server/ReactDOMServerLegacyFormatConfig.js b/packages/react-dom/src/server/ReactDOMServerLegacyFormatConfig.js
index 7373e71681761..5b0798b737129 100644
--- a/packages/react-dom/src/server/ReactDOMServerLegacyFormatConfig.js
+++ b/packages/react-dom/src/server/ReactDOMServerLegacyFormatConfig.js
@@ -34,9 +34,7 @@ export type ResponseState = {
   placeholderPrefix: PrecomputedChunk,
   segmentPrefix: PrecomputedChunk,
   boundaryPrefix: string,
-  opaqueIdentifierPrefix: string,
   nextSuspenseID: number,
-  nextOpaqueID: number,
   sentCompleteSegmentFunction: boolean,
   sentCompleteBoundaryFunction: boolean,
   sentClientRenderFunction: boolean,
@@ -56,9 +54,7 @@ export function createResponseState(
     placeholderPrefix: responseState.placeholderPrefix,
     segmentPrefix: responseState.segmentPrefix,
     boundaryPrefix: responseState.boundaryPrefix,
-    opaqueIdentifierPrefix: responseState.opaqueIdentifierPrefix,
     nextSuspenseID: responseState.nextSuspenseID,
-    nextOpaqueID: responseState.nextOpaqueID,
     sentCompleteSegmentFunction: responseState.sentCompleteSegmentFunction,
     sentCompleteBoundaryFunction: responseState.sentCompleteBoundaryFunction,
     sentClientRenderFunction: responseState.sentClientRenderFunction,
@@ -77,14 +73,12 @@ export function createRootFormatContext(): FormatContext {
 export type {
   FormatContext,
   SuspenseBoundaryID,
-  OpaqueIDType,
 } from './ReactDOMServerFormatConfig';
 
 export {
   getChildFormatContext,
   UNINITIALIZED_SUSPENSE_BOUNDARY_ID,
   assignSuspenseBoundaryID,
-  makeServerID,
   pushStartInstance,
   pushEndInstance,
   pushStartCompletedSuspenseBoundary,
diff --git a/packages/react-dom/src/server/ReactPartialRenderer.js b/packages/react-dom/src/server/ReactPartialRenderer.js
index 479a828a46e1f..1902dc65690c8 100644
--- a/packages/react-dom/src/server/ReactPartialRenderer.js
+++ b/packages/react-dom/src/server/ReactPartialRenderer.js
@@ -82,10 +82,6 @@ import {validateProperties as validateInputProperties} from '../shared/ReactDOMN
 import {validateProperties as validateUnknownProperties} from '../shared/ReactDOMUnknownPropertyHook';
 import hasOwnProperty from 'shared/hasOwnProperty';
 
-export type ServerOptions = {
-  identifierPrefix?: string,
-};
-
 // Based on reading the React.Children implementation. TODO: type this somewhere?
 type ReactNode = string | number | ReactElement;
 type FlatReactChildren = Array<null | ReactNode>;
@@ -784,14 +780,7 @@ class ReactDOMServerRenderer {
   contextValueStack: Array<any>;
   contextProviderStack: ?Array<ReactProvider<any>>; // DEV-only
 
-  uniqueID: number;
-  identifierPrefix: string;
-
-  constructor(
-    children: mixed,
-    makeStaticMarkup: boolean,
-    options?: ServerOptions,
-  ) {
+  constructor(children: mixed, makeStaticMarkup: boolean) {
     const flatChildren = flattenTopLevelChildren(children);
 
     const topFrame: Frame = {
@@ -820,10 +809,6 @@ class ReactDOMServerRenderer {
     this.contextStack = [];
     this.contextValueStack = [];
 
-    // useOpaqueIdentifier ID
-    this.uniqueID = 0;
-    this.identifierPrefix = (options && options.identifierPrefix) || '';
-
     if (__DEV__) {
       this.contextProviderStack = [];
     }
diff --git a/packages/react-dom/src/server/ReactPartialRendererHooks.js b/packages/react-dom/src/server/ReactPartialRendererHooks.js
index 26f2dd00ee0c6..2940c47bde46d 100644
--- a/packages/react-dom/src/server/ReactPartialRendererHooks.js
+++ b/packages/react-dom/src/server/ReactPartialRendererHooks.js
@@ -41,8 +41,6 @@ type Hook = {|
   next: Hook | null,
 |};
 
-type OpaqueIDType = string;
-
 let currentlyRenderingComponent: Object | null = null;
 let firstWorkInProgressHook: Hook | null = null;
 let workInProgressHook: Hook | null = null;
@@ -511,15 +509,7 @@ function useTransition(): [boolean, (callback: () => void) => void] {
   return [false, startTransition];
 }
 
-function useOpaqueIdentifier(): OpaqueIDType {
-  return (
-    (currentPartialRenderer.identifierPrefix || '') +
-    'R:' +
-    (currentPartialRenderer.uniqueID++).toString(36)
-  );
-}
-
-function useId(): OpaqueIDType {
+function useId(): string {
   throw new Error('Not implemented.');
 }
 
@@ -552,7 +542,6 @@ export const Dispatcher: DispatcherType = {
   useDebugValue: noop,
   useDeferredValue,
   useTransition,
-  useOpaqueIdentifier,
   useId,
   // Subscriptions are not setup in a server environment.
   useMutableSource,
diff --git a/packages/react-native-renderer/src/ReactFabricHostConfig.js b/packages/react-native-renderer/src/ReactFabricHostConfig.js
index c71a9050211cf..727b782efd768 100644
--- a/packages/react-native-renderer/src/ReactFabricHostConfig.js
+++ b/packages/react-native-renderer/src/ReactFabricHostConfig.js
@@ -84,8 +84,6 @@ export type UpdatePayload = Object;
 export type TimeoutHandle = TimeoutID;
 export type NoTimeout = -1;
 
-export type OpaqueIDType = void;
-
 export type RendererInspectionConfig = $ReadOnly<{|
   // Deprecated. Replaced with getInspectorDataForViewAtPoint.
   getInspectorDataForViewTag?: (tag: number) => Object,
@@ -512,24 +510,6 @@ export function getInstanceFromNode(node: any) {
   throw new Error('Not yet implemented.');
 }
 
-export function isOpaqueHydratingObject(value: mixed): boolean {
-  throw new Error('Not yet implemented');
-}
-
-export function makeOpaqueHydratingObject(
-  attemptToReadValue: () => void,
-): OpaqueIDType {
-  throw new Error('Not yet implemented.');
-}
-
-export function makeClientId(): OpaqueIDType {
-  throw new Error('Not yet implemented');
-}
-
-export function makeClientIdInDEV(warnOnAccessInDEV: () => void): OpaqueIDType {
-  throw new Error('Not yet implemented');
-}
-
 export function beforeActiveInstanceBlur(internalInstanceHandle: Object) {
   // noop
 }
diff --git a/packages/react-native-renderer/src/ReactNativeHostConfig.js b/packages/react-native-renderer/src/ReactNativeHostConfig.js
index 769f46e852a2f..10c5e37f41bcc 100644
--- a/packages/react-native-renderer/src/ReactNativeHostConfig.js
+++ b/packages/react-native-renderer/src/ReactNativeHostConfig.js
@@ -43,7 +43,6 @@ export type ChildSet = void; // Unused
 
 export type TimeoutHandle = TimeoutID;
 export type NoTimeout = -1;
-export type OpaqueIDType = void;
 
 export type RendererInspectionConfig = $ReadOnly<{|
   // Deprecated. Replaced with getInspectorDataForViewAtPoint.
@@ -499,24 +498,6 @@ export function getInstanceFromNode(node: any) {
   throw new Error('Not yet implemented.');
 }
 
-export function isOpaqueHydratingObject(value: mixed): boolean {
-  throw new Error('Not yet implemented');
-}
-
-export function makeOpaqueHydratingObject(
-  attemptToReadValue: () => void,
-): OpaqueIDType {
-  throw new Error('Not yet implemented.');
-}
-
-export function makeClientId(): OpaqueIDType {
-  throw new Error('Not yet implemented');
-}
-
-export function makeClientIdInDEV(warnOnAccessInDEV: () => void): OpaqueIDType {
-  throw new Error('Not yet implemented');
-}
-
 export function beforeActiveInstanceBlur(internalInstanceHandle: Object) {
   // noop
 }
diff --git a/packages/react-native-renderer/src/server/ReactNativeServerFormatConfig.js b/packages/react-native-renderer/src/server/ReactNativeServerFormatConfig.js
index 3daa48f420b16..5b12d810bbe0f 100644
--- a/packages/react-native-renderer/src/server/ReactNativeServerFormatConfig.js
+++ b/packages/react-native-renderer/src/server/ReactNativeServerFormatConfig.js
@@ -59,14 +59,12 @@ SUSPENSE_UPDATE_TO_CLIENT_RENDER[0] = SUSPENSE_UPDATE_TO_CLIENT_RENDER_TAG;
 // Per response,
 export type ResponseState = {
   nextSuspenseID: number,
-  nextOpaqueID: number,
 };
 
 // Allows us to keep track of what we've already written so we can refer back to it.
 export function createResponseState(): ResponseState {
   return {
     nextSuspenseID: 0,
-    nextOpaqueID: 0,
   };
 }
 
@@ -109,21 +107,6 @@ export function assignSuspenseBoundaryID(
   return responseState.nextSuspenseID++;
 }
 
-export type OpaqueIDType = number;
-
-export function makeServerID(
-  responseState: null | ResponseState,
-): OpaqueIDType {
-  if (responseState === null) {
-    throw new Error(
-      'Invalid hook call. Hooks can only be called inside of the body of a function component.',
-    );
-  }
-
-  // TODO: This is not deterministic since it's created during render.
-  return responseState.nextOpaqueID++;
-}
-
 const RAW_TEXT = stringToPrecomputedChunk('RCTRawText');
 
 export function pushTextInstance(
diff --git a/packages/react-noop-renderer/src/ReactNoopServer.js b/packages/react-noop-renderer/src/ReactNoopServer.js
index efcf727eac896..d217b16e50bfd 100644
--- a/packages/react-noop-renderer/src/ReactNoopServer.js
+++ b/packages/react-noop-renderer/src/ReactNoopServer.js
@@ -53,8 +53,6 @@ type Destination = {
 
 const POP = Buffer.from('/', 'utf8');
 
-let opaqueID = 0;
-
 const ReactNoopServer = ReactFizzServer({
   scheduleWork(callback: () => void) {
     callback();
@@ -88,10 +86,6 @@ const ReactNoopServer = ReactFizzServer({
     return {state: 'pending', children: []};
   },
 
-  makeServerID(): number {
-    return opaqueID++;
-  },
-
   getChildFormatContext(): null {
     return null;
   },
diff --git a/packages/react-reconciler/src/ReactFiberHooks.new.js b/packages/react-reconciler/src/ReactFiberHooks.new.js
index a1d7009a85a43..1238d673725ac 100644
--- a/packages/react-reconciler/src/ReactFiberHooks.new.js
+++ b/packages/react-reconciler/src/ReactFiberHooks.new.js
@@ -17,7 +17,6 @@ import type {Fiber, Dispatcher, HookType} from './ReactInternalTypes';
 import type {Lanes, Lane} from './ReactFiberLane.new';
 import type {HookFlags} from './ReactHookEffectTags';
 import type {FiberRoot} from './ReactInternalTypes';
-import type {OpaqueIDType} from './ReactFiberHostConfig';
 import type {Cache} from './ReactFiberCacheComponent.new';
 import type {Flags} from './ReactFiberFlags';
 
@@ -95,18 +94,12 @@ import {
   checkIfWorkInProgressReceivedUpdate,
 } from './ReactFiberBeginWork.new';
 import {getIsHydrating} from './ReactFiberHydrationContext.new';
-import {
-  makeClientId,
-  makeClientIdInDEV,
-  makeOpaqueHydratingObject,
-} from './ReactFiberHostConfig';
 import {
   getWorkInProgressVersion,
   markSourceAsDirty,
   setWorkInProgressVersion,
   warnAboutMultipleRenderersDEV,
 } from './ReactMutableSource.new';
-import {getIsRendering} from './ReactCurrentFiber';
 import {logStateUpdateScheduled} from './DebugTracing';
 import {markStateUpdateScheduled} from './SchedulingProfiler';
 import {createCache, CacheContext} from './ReactFiberCacheComponent.new';
@@ -139,10 +132,8 @@ export type UpdateQueue<S, A> = {|
 |};
 
 let didWarnAboutMismatchedHooksForComponent;
-let didWarnAboutUseOpaqueIdentifier;
 let didWarnUncachedGetSnapshot;
 if (__DEV__) {
-  didWarnAboutUseOpaqueIdentifier = {};
   didWarnAboutMismatchedHooksForComponent = new Set();
 }
 
@@ -2045,94 +2036,6 @@ export function getIsUpdatingOpaqueValueInRenderPhaseInDEV(): boolean | void {
   }
 }
 
-function warnOnOpaqueIdentifierAccessInDEV(fiber) {
-  if (__DEV__) {
-    // TODO: Should warn in effects and callbacks, too
-    const name = getComponentNameFromFiber(fiber) || 'Unknown';
-    if (getIsRendering() && !didWarnAboutUseOpaqueIdentifier[name]) {
-      console.error(
-        'The object passed back from useOpaqueIdentifier is meant to be ' +
-          'passed through to attributes only. Do not read the ' +
-          'value directly.',
-      );
-      didWarnAboutUseOpaqueIdentifier[name] = true;
-    }
-  }
-}
-
-function mountOpaqueIdentifier(): OpaqueIDType | void {
-  const makeId = __DEV__
-    ? makeClientIdInDEV.bind(
-        null,
-        warnOnOpaqueIdentifierAccessInDEV.bind(null, currentlyRenderingFiber),
-      )
-    : makeClientId;
-
-  if (getIsHydrating()) {
-    let didUpgrade = false;
-    const fiber = currentlyRenderingFiber;
-    const readValue = () => {
-      if (!didUpgrade) {
-        // Only upgrade once. This works even inside the render phase because
-        // the update is added to a shared queue, which outlasts the
-        // in-progress render.
-        didUpgrade = true;
-        if (__DEV__) {
-          isUpdatingOpaqueValueInRenderPhase = true;
-          setId(makeId());
-          isUpdatingOpaqueValueInRenderPhase = false;
-          warnOnOpaqueIdentifierAccessInDEV(fiber);
-        } else {
-          setId(makeId());
-        }
-      }
-
-      throw new Error(
-        'The object passed back from useOpaqueIdentifier is meant to be ' +
-          'passed through to attributes only. Do not read the value directly.',
-      );
-    };
-    const id = makeOpaqueHydratingObject(readValue);
-
-    const setId = mountState(id)[1];
-
-    if ((currentlyRenderingFiber.mode & ConcurrentMode) === NoMode) {
-      if (
-        __DEV__ &&
-        enableStrictEffects &&
-        (currentlyRenderingFiber.mode & StrictEffectsMode) === NoMode
-      ) {
-        currentlyRenderingFiber.flags |= MountPassiveDevEffect | PassiveEffect;
-      } else {
-        currentlyRenderingFiber.flags |= PassiveEffect;
-      }
-      pushEffect(
-        HookHasEffect | HookPassive,
-        () => {
-          setId(makeId());
-        },
-        undefined,
-        null,
-      );
-    }
-    return id;
-  } else {
-    const id = makeId();
-    mountState(id);
-    return id;
-  }
-}
-
-function updateOpaqueIdentifier(): OpaqueIDType | void {
-  const id = updateState(undefined)[0];
-  return id;
-}
-
-function rerenderOpaqueIdentifier(): OpaqueIDType | void {
-  const id = rerenderState(undefined)[0];
-  return id;
-}
-
 function mountId(): string {
   const hook = mountWorkInProgressHook();
 
@@ -2481,7 +2384,6 @@ export const ContextOnlyDispatcher: Dispatcher = {
   useTransition: throwInvalidHookError,
   useMutableSource: throwInvalidHookError,
   useSyncExternalStore: throwInvalidHookError,
-  useOpaqueIdentifier: throwInvalidHookError,
   useId: throwInvalidHookError,
 
   unstable_isNewReconciler: enableNewReconciler,
@@ -2510,7 +2412,6 @@ const HooksDispatcherOnMount: Dispatcher = {
   useTransition: mountTransition,
   useMutableSource: mountMutableSource,
   useSyncExternalStore: mountSyncExternalStore,
-  useOpaqueIdentifier: mountOpaqueIdentifier,
   useId: mountId,
 
   unstable_isNewReconciler: enableNewReconciler,
@@ -2539,7 +2440,6 @@ const HooksDispatcherOnUpdate: Dispatcher = {
   useTransition: updateTransition,
   useMutableSource: updateMutableSource,
   useSyncExternalStore: updateSyncExternalStore,
-  useOpaqueIdentifier: updateOpaqueIdentifier,
   useId: updateId,
 
   unstable_isNewReconciler: enableNewReconciler,
@@ -2568,7 +2468,6 @@ const HooksDispatcherOnRerender: Dispatcher = {
   useTransition: rerenderTransition,
   useMutableSource: updateMutableSource,
   useSyncExternalStore: mountSyncExternalStore,
-  useOpaqueIdentifier: rerenderOpaqueIdentifier,
   useId: updateId,
 
   unstable_isNewReconciler: enableNewReconciler,
@@ -2736,11 +2635,6 @@ if (__DEV__) {
       mountHookTypesDev();
       return mountSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      mountHookTypesDev();
-      return mountOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       mountHookTypesDev();
@@ -2883,11 +2777,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return mountSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      updateHookTypesDev();
-      return mountOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       updateHookTypesDev();
@@ -3030,11 +2919,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      updateHookTypesDev();
-      return updateOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       updateHookTypesDev();
@@ -3178,11 +3062,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      updateHookTypesDev();
-      return rerenderOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       updateHookTypesDev();
@@ -3341,12 +3220,6 @@ if (__DEV__) {
       mountHookTypesDev();
       return mountSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      warnInvalidHookAccess();
-      mountHookTypesDev();
-      return mountOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       warnInvalidHookAccess();
@@ -3506,12 +3379,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      warnInvalidHookAccess();
-      updateHookTypesDev();
-      return updateOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       warnInvalidHookAccess();
@@ -3672,12 +3539,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      warnInvalidHookAccess();
-      updateHookTypesDev();
-      return rerenderOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       warnInvalidHookAccess();
diff --git a/packages/react-reconciler/src/ReactFiberHooks.old.js b/packages/react-reconciler/src/ReactFiberHooks.old.js
index 167698271dbac..3b0b87cb1ab7c 100644
--- a/packages/react-reconciler/src/ReactFiberHooks.old.js
+++ b/packages/react-reconciler/src/ReactFiberHooks.old.js
@@ -17,7 +17,6 @@ import type {Fiber, Dispatcher, HookType} from './ReactInternalTypes';
 import type {Lanes, Lane} from './ReactFiberLane.old';
 import type {HookFlags} from './ReactHookEffectTags';
 import type {FiberRoot} from './ReactInternalTypes';
-import type {OpaqueIDType} from './ReactFiberHostConfig';
 import type {Cache} from './ReactFiberCacheComponent.old';
 import type {Flags} from './ReactFiberFlags';
 
@@ -95,18 +94,12 @@ import {
   checkIfWorkInProgressReceivedUpdate,
 } from './ReactFiberBeginWork.old';
 import {getIsHydrating} from './ReactFiberHydrationContext.old';
-import {
-  makeClientId,
-  makeClientIdInDEV,
-  makeOpaqueHydratingObject,
-} from './ReactFiberHostConfig';
 import {
   getWorkInProgressVersion,
   markSourceAsDirty,
   setWorkInProgressVersion,
   warnAboutMultipleRenderersDEV,
 } from './ReactMutableSource.old';
-import {getIsRendering} from './ReactCurrentFiber';
 import {logStateUpdateScheduled} from './DebugTracing';
 import {markStateUpdateScheduled} from './SchedulingProfiler';
 import {createCache, CacheContext} from './ReactFiberCacheComponent.old';
@@ -139,10 +132,8 @@ export type UpdateQueue<S, A> = {|
 |};
 
 let didWarnAboutMismatchedHooksForComponent;
-let didWarnAboutUseOpaqueIdentifier;
 let didWarnUncachedGetSnapshot;
 if (__DEV__) {
-  didWarnAboutUseOpaqueIdentifier = {};
   didWarnAboutMismatchedHooksForComponent = new Set();
 }
 
@@ -2045,94 +2036,6 @@ export function getIsUpdatingOpaqueValueInRenderPhaseInDEV(): boolean | void {
   }
 }
 
-function warnOnOpaqueIdentifierAccessInDEV(fiber) {
-  if (__DEV__) {
-    // TODO: Should warn in effects and callbacks, too
-    const name = getComponentNameFromFiber(fiber) || 'Unknown';
-    if (getIsRendering() && !didWarnAboutUseOpaqueIdentifier[name]) {
-      console.error(
-        'The object passed back from useOpaqueIdentifier is meant to be ' +
-          'passed through to attributes only. Do not read the ' +
-          'value directly.',
-      );
-      didWarnAboutUseOpaqueIdentifier[name] = true;
-    }
-  }
-}
-
-function mountOpaqueIdentifier(): OpaqueIDType | void {
-  const makeId = __DEV__
-    ? makeClientIdInDEV.bind(
-        null,
-        warnOnOpaqueIdentifierAccessInDEV.bind(null, currentlyRenderingFiber),
-      )
-    : makeClientId;
-
-  if (getIsHydrating()) {
-    let didUpgrade = false;
-    const fiber = currentlyRenderingFiber;
-    const readValue = () => {
-      if (!didUpgrade) {
-        // Only upgrade once. This works even inside the render phase because
-        // the update is added to a shared queue, which outlasts the
-        // in-progress render.
-        didUpgrade = true;
-        if (__DEV__) {
-          isUpdatingOpaqueValueInRenderPhase = true;
-          setId(makeId());
-          isUpdatingOpaqueValueInRenderPhase = false;
-          warnOnOpaqueIdentifierAccessInDEV(fiber);
-        } else {
-          setId(makeId());
-        }
-      }
-
-      throw new Error(
-        'The object passed back from useOpaqueIdentifier is meant to be ' +
-          'passed through to attributes only. Do not read the value directly.',
-      );
-    };
-    const id = makeOpaqueHydratingObject(readValue);
-
-    const setId = mountState(id)[1];
-
-    if ((currentlyRenderingFiber.mode & ConcurrentMode) === NoMode) {
-      if (
-        __DEV__ &&
-        enableStrictEffects &&
-        (currentlyRenderingFiber.mode & StrictEffectsMode) === NoMode
-      ) {
-        currentlyRenderingFiber.flags |= MountPassiveDevEffect | PassiveEffect;
-      } else {
-        currentlyRenderingFiber.flags |= PassiveEffect;
-      }
-      pushEffect(
-        HookHasEffect | HookPassive,
-        () => {
-          setId(makeId());
-        },
-        undefined,
-        null,
-      );
-    }
-    return id;
-  } else {
-    const id = makeId();
-    mountState(id);
-    return id;
-  }
-}
-
-function updateOpaqueIdentifier(): OpaqueIDType | void {
-  const id = updateState(undefined)[0];
-  return id;
-}
-
-function rerenderOpaqueIdentifier(): OpaqueIDType | void {
-  const id = rerenderState(undefined)[0];
-  return id;
-}
-
 function mountId(): string {
   const hook = mountWorkInProgressHook();
 
@@ -2481,7 +2384,6 @@ export const ContextOnlyDispatcher: Dispatcher = {
   useTransition: throwInvalidHookError,
   useMutableSource: throwInvalidHookError,
   useSyncExternalStore: throwInvalidHookError,
-  useOpaqueIdentifier: throwInvalidHookError,
   useId: throwInvalidHookError,
 
   unstable_isNewReconciler: enableNewReconciler,
@@ -2510,7 +2412,6 @@ const HooksDispatcherOnMount: Dispatcher = {
   useTransition: mountTransition,
   useMutableSource: mountMutableSource,
   useSyncExternalStore: mountSyncExternalStore,
-  useOpaqueIdentifier: mountOpaqueIdentifier,
   useId: mountId,
 
   unstable_isNewReconciler: enableNewReconciler,
@@ -2539,7 +2440,6 @@ const HooksDispatcherOnUpdate: Dispatcher = {
   useTransition: updateTransition,
   useMutableSource: updateMutableSource,
   useSyncExternalStore: updateSyncExternalStore,
-  useOpaqueIdentifier: updateOpaqueIdentifier,
   useId: updateId,
 
   unstable_isNewReconciler: enableNewReconciler,
@@ -2568,7 +2468,6 @@ const HooksDispatcherOnRerender: Dispatcher = {
   useTransition: rerenderTransition,
   useMutableSource: updateMutableSource,
   useSyncExternalStore: mountSyncExternalStore,
-  useOpaqueIdentifier: rerenderOpaqueIdentifier,
   useId: updateId,
 
   unstable_isNewReconciler: enableNewReconciler,
@@ -2736,11 +2635,6 @@ if (__DEV__) {
       mountHookTypesDev();
       return mountSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      mountHookTypesDev();
-      return mountOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       mountHookTypesDev();
@@ -2883,11 +2777,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return mountSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      updateHookTypesDev();
-      return mountOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       updateHookTypesDev();
@@ -3030,11 +2919,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      updateHookTypesDev();
-      return updateOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       updateHookTypesDev();
@@ -3178,11 +3062,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      updateHookTypesDev();
-      return rerenderOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       updateHookTypesDev();
@@ -3341,12 +3220,6 @@ if (__DEV__) {
       mountHookTypesDev();
       return mountSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      warnInvalidHookAccess();
-      mountHookTypesDev();
-      return mountOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       warnInvalidHookAccess();
@@ -3506,12 +3379,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      warnInvalidHookAccess();
-      updateHookTypesDev();
-      return updateOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       warnInvalidHookAccess();
@@ -3672,12 +3539,6 @@ if (__DEV__) {
       updateHookTypesDev();
       return updateSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
     },
-    useOpaqueIdentifier(): OpaqueIDType | void {
-      currentHookNameInDev = 'useOpaqueIdentifier';
-      warnInvalidHookAccess();
-      updateHookTypesDev();
-      return rerenderOpaqueIdentifier();
-    },
     useId(): string {
       currentHookNameInDev = 'useId';
       warnInvalidHookAccess();
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.new.js b/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
index e35e5515bb0bf..71bf8175105d6 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
@@ -474,8 +474,7 @@ export function scheduleUpdateOnFiber(
     // if the update originates from user space (with the exception of local
     // hook updates, which are handled differently and don't reach this
     // function), but there are some internal React features that use this as
-    // an implementation detail, like selective hydration
-    // and useOpaqueIdentifier.
+    // an implementation detail, like selective hydration.
     warnAboutRenderPhaseUpdatesInDEV(fiber);
 
     // Track lanes that were updated during the render phase
@@ -898,12 +897,10 @@ function recoverFromConcurrentError(root, errorRetryLanes) {
       exitStatus === RootErrored &&
       workInProgressRootRenderPhaseUpdatedLanes !== NoLanes
     ) {
-      // There was a render phase update during this render. This was likely a
-      // useOpaqueIdentifier hook upgrading itself to a client ID. Try rendering
-      // again. This time, the component will use a client ID and will proceed
-      // without throwing. If multiple IDs upgrade as a result of the same
-      // update, we will have to do multiple render passes. To protect against
-      // an inifinite loop, eventually we'll give up.
+      // There was a render phase update during this render. Some internal React
+      // implementation details may use this as a trick to schedule another
+      // render pass. To protect against an inifinite loop, eventually
+      // we'll give up.
       continue;
     }
     break;
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.old.js b/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
index cde46adb01ab0..8be4630dc079d 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
@@ -474,8 +474,7 @@ export function scheduleUpdateOnFiber(
     // if the update originates from user space (with the exception of local
     // hook updates, which are handled differently and don't reach this
     // function), but there are some internal React features that use this as
-    // an implementation detail, like selective hydration
-    // and useOpaqueIdentifier.
+    // an implementation detail, like selective hydration.
     warnAboutRenderPhaseUpdatesInDEV(fiber);
 
     // Track lanes that were updated during the render phase
@@ -898,12 +897,10 @@ function recoverFromConcurrentError(root, errorRetryLanes) {
       exitStatus === RootErrored &&
       workInProgressRootRenderPhaseUpdatedLanes !== NoLanes
     ) {
-      // There was a render phase update during this render. This was likely a
-      // useOpaqueIdentifier hook upgrading itself to a client ID. Try rendering
-      // again. This time, the component will use a client ID and will proceed
-      // without throwing. If multiple IDs upgrade as a result of the same
-      // update, we will have to do multiple render passes. To protect against
-      // an inifinite loop, eventually we'll give up.
+      // There was a render phase update during this render. Some internal React
+      // implementation details may use this as a trick to schedule another
+      // render pass. To protect against an inifinite loop, eventually
+      // we'll give up.
       continue;
     }
     break;
diff --git a/packages/react-reconciler/src/ReactInternalTypes.js b/packages/react-reconciler/src/ReactInternalTypes.js
index 9dac4f40aad53..db964103836da 100644
--- a/packages/react-reconciler/src/ReactInternalTypes.js
+++ b/packages/react-reconciler/src/ReactInternalTypes.js
@@ -43,7 +43,6 @@ export type HookType =
   | 'useTransition'
   | 'useMutableSource'
   | 'useSyncExternalStore'
-  | 'useOpaqueIdentifier'
   | 'useId'
   | 'useCacheRefresh';
 
@@ -317,7 +316,6 @@ export type Dispatcher = {|
     getSnapshot: () => T,
     getServerSnapshot?: () => T,
   ): T,
-  useOpaqueIdentifier(): any,
   useId(): string,
   useCacheRefresh?: () => <T>(?() => T, ?T) => void,
 
diff --git a/packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js b/packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js
index cc842bd16d22f..55ce08b45450b 100644
--- a/packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js
@@ -1916,14 +1916,14 @@ describe('ReactIncrementalErrorHandling', () => {
   });
 
   it("does not infinite loop if there's a render phase update in the same render as an error", async () => {
-    // useOpaqueIdentifier uses an render phase update as an implementation
-    // detail. When an error is accompanied by a render phase update, we assume
-    // that it comes from useOpaqueIdentifier, because render phase updates
-    // triggered from userspace are not allowed (we log a warning). So we keep
-    // attempting to recover until no more opaque identifiers need to be
-    // upgraded. However, we should give up after some point to prevent an
-    // infinite loop in the case where there is (by accident) a render phase
-    // triggered from userspace.
+    // Some React features may schedule a render phase update as an
+    // implementation detail. When an error is accompanied by a render phase
+    // update, we assume that it comes from React internals, because render
+    // phase updates triggered from userspace are not allowed (we log a
+    // warning). So we keep attempting to recover until no more opaque
+    // identifiers need to be upgraded. However, we should give up after some
+    // point to prevent an infinite loop in the case where there is (by
+    // accident) a render phase triggered from userspace.
 
     spyOnDev(console, 'error');
 
diff --git a/packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js b/packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js
index 29d4fd7e79893..6535d8d3fdec3 100644
--- a/packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js
+++ b/packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js
@@ -38,7 +38,6 @@ export opaque type ChildSet = mixed; // eslint-disable-line no-undef
 export opaque type TimeoutHandle = mixed; // eslint-disable-line no-undef
 export opaque type NoTimeout = mixed; // eslint-disable-line no-undef
 export opaque type RendererInspectionConfig = mixed; // eslint-disable-line no-undef
-export opaque type OpaqueIDType = mixed;
 export type EventResponder = any;
 
 export const getPublicInstance = $$$hostConfig.getPublicInstance;
@@ -62,11 +61,6 @@ export const supportsMutation = $$$hostConfig.supportsMutation;
 export const supportsPersistence = $$$hostConfig.supportsPersistence;
 export const supportsHydration = $$$hostConfig.supportsHydration;
 export const getInstanceFromNode = $$$hostConfig.getInstanceFromNode;
-export const isOpaqueHydratingObject = $$$hostConfig.isOpaqueHydratingObject;
-export const makeOpaqueHydratingObject =
-  $$$hostConfig.makeOpaqueHydratingObject;
-export const makeClientId = $$$hostConfig.makeClientId;
-export const makeClientIdInDEV = $$$hostConfig.makeClientIdInDEV;
 export const beforeActiveInstanceBlur = $$$hostConfig.beforeActiveInstanceBlur;
 export const afterActiveInstanceBlur = $$$hostConfig.afterActiveInstanceBlur;
 export const preparePortalMount = $$$hostConfig.preparePortalMount;
diff --git a/packages/react-server/src/ReactFizzHooks.js b/packages/react-server/src/ReactFizzHooks.js
index bf1a2d56e0f93..7b31e6b37ed9e 100644
--- a/packages/react-server/src/ReactFizzHooks.js
+++ b/packages/react-server/src/ReactFizzHooks.js
@@ -16,14 +16,12 @@ import type {
   ReactContext,
 } from 'shared/ReactTypes';
 
-import type {ResponseState, OpaqueIDType} from './ReactServerFormatConfig';
+import type {ResponseState} from './ReactServerFormatConfig';
 import type {Task} from './ReactFizzServer';
 
 import {readContext as readContextImpl} from './ReactFizzNewContext';
 import {getTreeId} from './ReactFizzTreeContext';
 
-import {makeServerID} from './ReactServerFormatConfig';
-
 import {enableCache} from 'shared/ReactFeatureFlags';
 import is from 'shared/objectIs';
 
@@ -509,10 +507,6 @@ function useTransition(): [boolean, (callback: () => void) => void] {
   return [false, unsupportedStartTransition];
 }
 
-function useOpaqueIdentifier(): OpaqueIDType {
-  return makeServerID(currentResponseState);
-}
-
 function useId(): string {
   const task: Task = (currentlyRenderingTask: any);
   const treeId = getTreeId(task.treeContext);
@@ -559,7 +553,6 @@ export const Dispatcher: DispatcherType = {
   useDebugValue: noop,
   useDeferredValue,
   useTransition,
-  useOpaqueIdentifier,
   useId,
   // Subscriptions are not setup in a server environment.
   useMutableSource,
diff --git a/packages/react-server/src/ReactFlightServer.js b/packages/react-server/src/ReactFlightServer.js
index bba34065cc268..418fbb8241a66 100644
--- a/packages/react-server/src/ReactFlightServer.js
+++ b/packages/react-server/src/ReactFlightServer.js
@@ -845,7 +845,6 @@ const Dispatcher: DispatcherType = {
   useLayoutEffect: (unsupportedHook: any),
   useImperativeHandle: (unsupportedHook: any),
   useEffect: (unsupportedHook: any),
-  useOpaqueIdentifier: (unsupportedHook: any),
   useId: (unsupportedHook: any),
   useMutableSource: (unsupportedHook: any),
   useSyncExternalStore: (unsupportedHook: any),
diff --git a/packages/react-server/src/forks/ReactServerFormatConfig.custom.js b/packages/react-server/src/forks/ReactServerFormatConfig.custom.js
index 8cfe59ce1628c..f246ddab8b5bf 100644
--- a/packages/react-server/src/forks/ReactServerFormatConfig.custom.js
+++ b/packages/react-server/src/forks/ReactServerFormatConfig.custom.js
@@ -28,7 +28,6 @@ export opaque type Destination = mixed; // eslint-disable-line no-undef
 export opaque type ResponseState = mixed;
 export opaque type FormatContext = mixed;
 export opaque type SuspenseBoundaryID = mixed;
-export opaque type OpaqueIDType = mixed;
 
 export const isPrimaryRenderer = false;
 
@@ -36,7 +35,6 @@ export const getChildFormatContext = $$$hostConfig.getChildFormatContext;
 export const UNINITIALIZED_SUSPENSE_BOUNDARY_ID =
   $$$hostConfig.UNINITIALIZED_SUSPENSE_BOUNDARY_ID;
 export const assignSuspenseBoundaryID = $$$hostConfig.assignSuspenseBoundaryID;
-export const makeServerID = $$$hostConfig.makeServerID;
 export const pushTextInstance = $$$hostConfig.pushTextInstance;
 export const pushStartInstance = $$$hostConfig.pushStartInstance;
 export const pushEndInstance = $$$hostConfig.pushEndInstance;
diff --git a/packages/react-suspense-test-utils/src/ReactSuspenseTestUtils.js b/packages/react-suspense-test-utils/src/ReactSuspenseTestUtils.js
index 731124ea51593..d75f1f7c9b453 100644
--- a/packages/react-suspense-test-utils/src/ReactSuspenseTestUtils.js
+++ b/packages/react-suspense-test-utils/src/ReactSuspenseTestUtils.js
@@ -42,7 +42,6 @@ export function waitForSuspense<T>(fn: () => T): Promise<T> {
     useDebugValue: unsupported,
     useDeferredValue: unsupported,
     useTransition: unsupported,
-    useOpaqueIdentifier: unsupported,
     useId: unsupported,
     useMutableSource: unsupported,
     useSyncExternalStore: unsupported,
diff --git a/packages/react-test-renderer/src/ReactTestHostConfig.js b/packages/react-test-renderer/src/ReactTestHostConfig.js
index 6cdadabe281a5..503b08efaf20b 100644
--- a/packages/react-test-renderer/src/ReactTestHostConfig.js
+++ b/packages/react-test-renderer/src/ReactTestHostConfig.js
@@ -7,7 +7,6 @@
  * @flow
  */
 
-import {REACT_OPAQUE_ID_TYPE} from 'shared/ReactSymbols';
 import isArray from 'shared/isArray';
 import {DefaultEventPriority} from 'react-reconciler/src/ReactEventPriorities';
 
@@ -40,12 +39,6 @@ export type ChildSet = void; // Unused
 export type TimeoutHandle = TimeoutID;
 export type NoTimeout = -1;
 export type EventResponder = any;
-export opaque type OpaqueIDType =
-  | string
-  | {
-      toString: () => string | void,
-      valueOf: () => string | void,
-    };
 
 export type RendererInspectionConfig = $ReadOnly<{||}>;
 
@@ -298,43 +291,6 @@ export function getInstanceFromNode(mockNode: Object) {
   return null;
 }
 
-let clientId: number = 0;
-export function makeClientId(): OpaqueIDType {
-  return 'c_' + (clientId++).toString(36);
-}
-
-export function makeClientIdInDEV(warnOnAccessInDEV: () => void): OpaqueIDType {
-  const id = 'c_' + (clientId++).toString(36);
-  return {
-    toString() {
-      warnOnAccessInDEV();
-      return id;
-    },
-    valueOf() {
-      warnOnAccessInDEV();
-      return id;
-    },
-  };
-}
-
-export function isOpaqueHydratingObject(value: mixed): boolean {
-  return (
-    value !== null &&
-    typeof value === 'object' &&
-    value.$$typeof === REACT_OPAQUE_ID_TYPE
-  );
-}
-
-export function makeOpaqueHydratingObject(
-  attemptToReadValue: () => void,
-): OpaqueIDType {
-  return {
-    $$typeof: REACT_OPAQUE_ID_TYPE,
-    toString: attemptToReadValue,
-    valueOf: attemptToReadValue,
-  };
-}
-
 export function beforeActiveInstanceBlur(internalInstanceHandle: Object) {
   // noop
 }
diff --git a/packages/react/index.classic.fb.js b/packages/react/index.classic.fb.js
index a2e678c580b2e..70bbc6112a56c 100644
--- a/packages/react/index.classic.fb.js
+++ b/packages/react/index.classic.fb.js
@@ -40,7 +40,6 @@ export {
   unstable_getCacheSignal,
   unstable_getCacheForType,
   unstable_useCacheRefresh,
-  unstable_useOpaqueIdentifier,
   unstable_useId,
   useCallback,
   useContext,
diff --git a/packages/react/index.experimental.js b/packages/react/index.experimental.js
index 20c22828583f5..bc3f4883bdb3d 100644
--- a/packages/react/index.experimental.js
+++ b/packages/react/index.experimental.js
@@ -36,7 +36,6 @@ export {
   unstable_getCacheSignal,
   unstable_getCacheForType,
   unstable_useCacheRefresh,
-  unstable_useOpaqueIdentifier,
   unstable_useId,
   useCallback,
   useContext,
diff --git a/packages/react/index.js b/packages/react/index.js
index 3108c06c55284..a27507524e50b 100644
--- a/packages/react/index.js
+++ b/packages/react/index.js
@@ -61,7 +61,6 @@ export {
   unstable_getCacheSignal,
   unstable_getCacheForType,
   unstable_useCacheRefresh,
-  unstable_useOpaqueIdentifier,
   unstable_useId,
   useCallback,
   useContext,
diff --git a/packages/react/index.modern.fb.js b/packages/react/index.modern.fb.js
index eef99fdabf2a4..922acfc158109 100644
--- a/packages/react/index.modern.fb.js
+++ b/packages/react/index.modern.fb.js
@@ -39,7 +39,6 @@ export {
   unstable_getCacheSignal,
   unstable_getCacheForType,
   unstable_useCacheRefresh,
-  unstable_useOpaqueIdentifier,
   unstable_useId,
   useCallback,
   useContext,
diff --git a/packages/react/index.stable.js b/packages/react/index.stable.js
index 517dc3f8fb2db..eb9673efd16ad 100644
--- a/packages/react/index.stable.js
+++ b/packages/react/index.stable.js
@@ -29,7 +29,6 @@ export {
   lazy,
   memo,
   startTransition,
-  unstable_useOpaqueIdentifier,
   unstable_useId,
   useCallback,
   useContext,
diff --git a/packages/react/src/React.js b/packages/react/src/React.js
index 868538c83f59b..5fe5b4d96b609 100644
--- a/packages/react/src/React.js
+++ b/packages/react/src/React.js
@@ -52,7 +52,6 @@ import {
   useState,
   useTransition,
   useDeferredValue,
-  useOpaqueIdentifier,
   useId,
   useCacheRefresh,
 } from './ReactHooks';
@@ -127,7 +126,6 @@ export {
   REACT_CACHE_TYPE as unstable_Cache,
   // enableScopeAPI
   REACT_SCOPE_TYPE as unstable_Scope,
-  useOpaqueIdentifier as unstable_useOpaqueIdentifier,
   useId as unstable_useId,
   act,
 };
diff --git a/packages/react/src/ReactHooks.js b/packages/react/src/ReactHooks.js
index 1f987de1671ba..12a5350083f38 100644
--- a/packages/react/src/ReactHooks.js
+++ b/packages/react/src/ReactHooks.js
@@ -14,7 +14,6 @@ import type {
   MutableSourceSubscribeFn,
   ReactContext,
 } from 'shared/ReactTypes';
-import type {OpaqueIDType} from 'react-reconciler/src/ReactFiberHostConfig';
 
 import ReactCurrentDispatcher from './ReactCurrentDispatcher';
 
@@ -169,11 +168,6 @@ export function useDeferredValue<T>(value: T): T {
   return dispatcher.useDeferredValue(value);
 }
 
-export function useOpaqueIdentifier(): OpaqueIDType | void {
-  const dispatcher = resolveDispatcher();
-  return dispatcher.useOpaqueIdentifier();
-}
-
 export function useId(): string {
   const dispatcher = resolveDispatcher();
   return dispatcher.useId();
diff --git a/packages/react/unstable-shared-subset.experimental.js b/packages/react/unstable-shared-subset.experimental.js
index d556400750b4c..7a9352f30199a 100644
--- a/packages/react/unstable-shared-subset.experimental.js
+++ b/packages/react/unstable-shared-subset.experimental.js
@@ -27,7 +27,6 @@ export {
   unstable_DebugTracingMode,
   unstable_getCacheSignal,
   unstable_getCacheForType,
-  unstable_useOpaqueIdentifier,
   unstable_useId,
   useCallback,
   useContext,
diff --git a/packages/shared/CheckStringCoercion.js b/packages/shared/CheckStringCoercion.js
index 9db9e7145ad4f..305572f8462c7 100644
--- a/packages/shared/CheckStringCoercion.js
+++ b/packages/shared/CheckStringCoercion.js
@@ -7,8 +7,6 @@
  * @flow
  */
 
-import {REACT_OPAQUE_ID_TYPE} from 'shared/ReactSymbols';
-
 /*
  * The `'' + value` pattern (used in in perf-sensitive code) throws for Symbol
  * and Temporal.* types. See https://github.com/facebook/react/pull/22064.
@@ -35,16 +33,6 @@ function typeName(value: mixed): string {
 // $FlowFixMe only called in DEV, so void return is not possible.
 function willCoercionThrow(value: mixed): boolean {
   if (__DEV__) {
-    if (
-      value !== null &&
-      typeof value === 'object' &&
-      value.$$typeof === REACT_OPAQUE_ID_TYPE
-    ) {
-      // OpaqueID type is expected to throw, so React will handle it. Not sure if
-      // it's expected that string coercion will throw, but we'll assume it's OK.
-      // See https://github.com/facebook/react/issues/20127.
-      return;
-    }
     try {
       testStringCoercion(value);
       return false;
diff --git a/packages/shared/ReactSymbols.js b/packages/shared/ReactSymbols.js
index c2fcba6324410..a50a06b150169 100644
--- a/packages/shared/ReactSymbols.js
+++ b/packages/shared/ReactSymbols.js
@@ -26,7 +26,6 @@ export let REACT_SUSPENSE_LIST_TYPE = 0xead8;
 export let REACT_MEMO_TYPE = 0xead3;
 export let REACT_LAZY_TYPE = 0xead4;
 export let REACT_SCOPE_TYPE = 0xead7;
-export let REACT_OPAQUE_ID_TYPE = 0xeae0;
 export let REACT_DEBUG_TRACING_MODE_TYPE = 0xeae1;
 export let REACT_OFFSCREEN_TYPE = 0xeae2;
 export let REACT_LEGACY_HIDDEN_TYPE = 0xeae3;
@@ -47,7 +46,6 @@ if (typeof Symbol === 'function' && Symbol.for) {
   REACT_MEMO_TYPE = symbolFor('react.memo');
   REACT_LAZY_TYPE = symbolFor('react.lazy');
   REACT_SCOPE_TYPE = symbolFor('react.scope');
-  REACT_OPAQUE_ID_TYPE = symbolFor('react.opaque.id');
   REACT_DEBUG_TRACING_MODE_TYPE = symbolFor('react.debug_trace_mode');
   REACT_OFFSCREEN_TYPE = symbolFor('react.offscreen');
   REACT_LEGACY_HIDDEN_TYPE = symbolFor('react.legacy_hidden');
diff --git a/scripts/error-codes/codes.json b/scripts/error-codes/codes.json
index aab5d62476cc3..93391eb309d49 100644
--- a/scripts/error-codes/codes.json
+++ b/scripts/error-codes/codes.json
@@ -342,7 +342,7 @@
   "352": "React Lazy Components are not yet supported on the server.",
   "353": "A server block should never encode any other slots. This is a bug in React.",
   "354": "getInspectorDataForViewAtPoint() is not available in production.",
-  "355": "The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. Do not read the value directly.",
+  "355": "The object passed back from useOpaqueIdentifier is meant to be passed through to attributes only. Do not read the value directly. (TODO: This feature was never released so we should be able to remove this error from the map.)",
   "356": "Could not read the cache.",
   "357": "The current renderer does not support React Scopes. This error is likely caused by a bug in React. Please file an issue.",
   "358": "Invalid update priority: %s. This is a bug in React.",