diff --git a/spec-dtslint/observables/zip-spec.ts b/spec-dtslint/observables/zip-spec.ts
index 19c21a71db..e37976e469 100644
--- a/spec-dtslint/observables/zip-spec.ts
+++ b/spec-dtslint/observables/zip-spec.ts
@@ -36,3 +36,14 @@ it('should return Array<T> when given a single observable', () => {
   const a = of(1); // $ExpectType Observable<number>
   const o1 = zip(a); // $ExpectType Observable<number[]>
 });
+
+it('should support union types', () => {
+  const u = Math.random() > 0.5 ? of(123) : of('abc');
+  const o = zip(u, u, u); // $ExpectType Observable<[string | number, string | number, string | number]>
+});
+
+it('should support different union types', () => {
+  const u = Math.random() > 0.5 ? of(123) : of('abc');
+  const u2 = Math.random() > 0.5 ? of(true) : of([1, 2, 3]);
+  const o = zip(u, u2); // $ExpectType Observable<[string | number, boolean | number[]]>
+});
diff --git a/src/internal/observable/zip.ts b/src/internal/observable/zip.ts
index f360913742..b32965bb34 100644
--- a/src/internal/observable/zip.ts
+++ b/src/internal/observable/zip.ts
@@ -2,7 +2,7 @@ import { Observable } from '../Observable';
 import { fromArray } from './fromArray';
 import { isArray } from '../util/isArray';
 import { Operator } from '../Operator';
-import { ObservableInput, PartialObserver } from '../types';
+import { ObservableInput, PartialObserver, ObservedValueOf } from '../types';
 import { Subscriber } from '../Subscriber';
 import { Subscription } from '../Subscription';
 import { OuterSubscriber } from '../OuterSubscriber';
@@ -12,33 +12,33 @@ import { iterator as Symbol_iterator } from '../../internal/symbol/iterator';
 
 /* tslint:disable:max-line-length */
 /** @deprecated resultSelector is no longer supported, pipe to map instead */
-export function zip<T, R>(v1: ObservableInput<T>, resultSelector: (v1: T) => R): Observable<R>;
+export function zip<O1 extends ObservableInput<any>, R>(v1: O1, resultSelector: (v1: ObservedValueOf<O1>) => R): Observable<R>;
 /** @deprecated resultSelector is no longer supported, pipe to map instead */
-export function zip<T, T2, R>(v1: ObservableInput<T>, v2: ObservableInput<T2>, resultSelector: (v1: T, v2: T2) => R): Observable<R>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, R>(v1: O1, v2: O2, resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>) => R): Observable<R>;
 /** @deprecated resultSelector is no longer supported, pipe to map instead */
-export function zip<T, T2, T3, R>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, resultSelector: (v1: T, v2: T2, v3: T3) => R): Observable<R>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, R>(v1: O1, v2: O2, v3: O3, resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>) => R): Observable<R>;
 /** @deprecated resultSelector is no longer supported, pipe to map instead */
-export function zip<T, T2, T3, T4, R>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4) => R): Observable<R>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, R>(v1: O1, v2: O2, v3: O3, v4: O4, resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>, v4: ObservedValueOf<O4>) => R): Observable<R>;
 /** @deprecated resultSelector is no longer supported, pipe to map instead */
-export function zip<T, T2, T3, T4, T5, R>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => R): Observable<R>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>, R>(v1: O1, v2: O2, v3: O3, v4: O4, v5: O5, resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>, v4: ObservedValueOf<O4>, v5: ObservedValueOf<O5>) => R): Observable<R>;
 /** @deprecated resultSelector is no longer supported, pipe to map instead */
-export function zip<T, T2, T3, T4, T5, T6, R>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>, resultSelector: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5, v6: T6) => R): Observable<R>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>, O6 extends ObservableInput<any>, R>(v1: O1, v2: O2, v3: O3, v4: O4, v5: O5, v6: O6, resultSelector: (v1: ObservedValueOf<O1>, v2: ObservedValueOf<O2>, v3: ObservedValueOf<O3>, v4: ObservedValueOf<O4>, v5: ObservedValueOf<O5>, v6: ObservedValueOf<O6>) => R): Observable<R>;
 
-export function zip<T, T2>(v1: ObservableInput<T>, v2: ObservableInput<T2>): Observable<[T, T2]>;
-export function zip<T, T2, T3>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>): Observable<[T, T2, T3]>;
-export function zip<T, T2, T3, T4>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>): Observable<[T, T2, T3, T4]>;
-export function zip<T, T2, T3, T4, T5>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>): Observable<[T, T2, T3, T4, T5]>;
-export function zip<T, T2, T3, T4, T5, T6>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>): Observable<[T, T2, T3, T4, T5, T6]>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>>(v1: O1, v2: O2): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>]>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>>(v1: O1, v2: O2, v3: O3): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>]>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>>(v1: O1, v2: O2, v3: O3, v4: O4): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>]>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>>(v1: O1, v2: O2, v3: O3, v4: O4, v5: O5): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>, ObservedValueOf<O5>]>;
+export function zip<O1 extends ObservableInput<any>, O2 extends ObservableInput<any>, O3 extends ObservableInput<any>, O4 extends ObservableInput<any>, O5 extends ObservableInput<any>, O6 extends ObservableInput<any>>(v1: O1, v2: O2, v3: O3, v4: O4, v5: O5, v6: O6): Observable<[ObservedValueOf<O1>, ObservedValueOf<O2>, ObservedValueOf<O3>, ObservedValueOf<O4>, ObservedValueOf<O5>, ObservedValueOf<O6>]>;
 
-export function zip<T>(array: ObservableInput<T>[]): Observable<T[]>;
+export function zip<O extends ObservableInput<any>>(array: O[]): Observable<ObservedValueOf<O>[]>;
 export function zip<R>(array: ObservableInput<any>[]): Observable<R>;
 /** @deprecated resultSelector is no longer supported, pipe to map instead */
-export function zip<T, R>(array: ObservableInput<T>[], resultSelector: (...values: Array<T>) => R): Observable<R>;
+export function zip<O extends ObservableInput<any>, R>(array: O[], resultSelector: (...values: ObservedValueOf<O>[]) => R): Observable<R>;
 /** @deprecated resultSelector is no longer supported, pipe to map instead */
-export function zip<R>(array: ObservableInput<any>[], resultSelector: (...values: Array<any>) => R): Observable<R>;
+export function zip<R>(array: ObservableInput<any>[], resultSelector: (...values: any[]) => R): Observable<R>;
 
-export function zip<T>(...observables: Array<ObservableInput<T>>): Observable<T[]>;
-export function zip<T, R>(...observables: Array<ObservableInput<T> | ((...values: Array<T>) => R)>): Observable<R>;
+export function zip<O extends ObservableInput<any>>(...observables: O[]): Observable<ObservedValueOf<O>[]>;
+export function zip<O extends ObservableInput<any>, R>(...observables: Array<O | ((...values: ObservedValueOf<O>[]) => R)>): Observable<R>;
 export function zip<R>(...observables: Array<ObservableInput<any> | ((...values: Array<any>) => R)>): Observable<R>;
 /* tslint:enable:max-line-length */
 
@@ -72,7 +72,9 @@ export function zip<R>(...observables: Array<ObservableInput<any> | ((...values:
  * @name zip
  * @owner Observable
  */
-export function zip<T, R>(...observables: Array<ObservableInput<any> | ((...values: Array<any>) => R)>): Observable<R> {
+export function zip<O extends ObservableInput<any>, R>(
+  ...observables: Array<O | ((...values: ObservedValueOf<O>[]) => R)>
+): Observable<ObservedValueOf<O>[]|R> {
   const resultSelector = <((...ys: Array<any>) => R)> observables[observables.length - 1];
   if (typeof resultSelector === 'function') {
     observables.pop();