diff --git a/src/lib/dialog/dialog-content-directives.ts b/src/lib/dialog/dialog-content-directives.ts
index a7c8e3875ef1..5f268182511b 100644
--- a/src/lib/dialog/dialog-content-directives.ts
+++ b/src/lib/dialog/dialog-content-directives.ts
@@ -9,7 +9,8 @@ import {MdDialogRef} from './dialog-ref';
   selector: 'button[md-dialog-close], button[mat-dialog-close]',
   host: {
     '(click)': 'dialogRef.close()',
-    '[attr.aria-label]': 'ariaLabel'
+    '[attr.aria-label]': 'ariaLabel',
+    'type': 'button', // Prevents accidental form submits.
   }
 })
 export class MdDialogClose {
diff --git a/src/lib/dialog/dialog.spec.ts b/src/lib/dialog/dialog.spec.ts
index 38243742b63c..6c81e45b682e 100644
--- a/src/lib/dialog/dialog.spec.ts
+++ b/src/lib/dialog/dialog.spec.ts
@@ -343,6 +343,12 @@ describe('MdDialog', () => {
       expect(button.getAttribute('aria-label')).toBe('Best close button ever');
     });
 
+    it('should override the "type" attribute of the close button', () => {
+      let button = overlayContainerElement.querySelector('button[md-dialog-close]');
+
+      expect(button.getAttribute('type')).toBe('button');
+    });
+
   });
 });