diff --git a/modules/store/spec/reducer_creator.spec.ts b/modules/store/spec/reducer_creator.spec.ts
index d673368162..ff2a2d4e7a 100644
--- a/modules/store/spec/reducer_creator.spec.ts
+++ b/modules/store/spec/reducer_creator.spec.ts
@@ -1,4 +1,3 @@
-import * as ngCore from '@angular/core';
 import { on, createReducer, createAction, props, union } from '@ngrx/store';
 import { expecter } from 'ts-snippet';
 
@@ -87,59 +86,6 @@ import {on} from './modules/store/src/reducer_creator';
         state = fooBarReducer(state, bar({ bar: 54 }));
         expect(state).toEqual(['[foobar] FOO', '[foobar] BAR']);
       });
-
-      describe('warning message when the same action type gets registered', () => {
-        it('should not warn when not violated', () => {
-          const spy = spyOn(console, 'warn');
-
-          const fooBarReducer = createReducer(
-            [],
-            on(foo, state => state),
-            on(bar, state => state)
-          );
-
-          expect(spy).not.toHaveBeenCalled();
-        });
-
-        it('should warn in dev mode', () => {
-          const spy = spyOn(console, 'warn');
-
-          const fooBarReducer = createReducer(
-            [],
-            on(foo, state => state),
-            on(bar, state => state),
-            on(foo, state => state)
-          );
-
-          expect(spy).toHaveBeenCalledTimes(1);
-        });
-
-        it('should warn in dev mode with multiple actions', () => {
-          const spy = spyOn(console, 'warn');
-
-          const fooBarReducer = createReducer(
-            [],
-            on(foo, foo, state => state),
-            on(bar, state => state)
-          );
-
-          expect(spy).toHaveBeenCalledTimes(1);
-        });
-
-        it('should not warn in prod mode', () => {
-          spyOn(ngCore, 'isDevMode').and.returnValue(false);
-          const spy = spyOn(console, 'warn');
-
-          const fooBarReducer = createReducer(
-            [],
-            on(foo, state => state),
-            on(bar, state => state),
-            on(foo, state => state)
-          );
-
-          expect(spy).not.toHaveBeenCalled();
-        });
-      });
     });
   });
 });
diff --git a/modules/store/src/reducer_creator.ts b/modules/store/src/reducer_creator.ts
index 95b85eb621..4ce7402686 100644
--- a/modules/store/src/reducer_creator.ts
+++ b/modules/store/src/reducer_creator.ts
@@ -1,4 +1,3 @@
-import { isDevMode } from '@angular/core';
 import { ActionCreator, ActionReducer, ActionType, Action } from './models';
 
 // Return type of the `on` fn.
@@ -185,18 +184,12 @@ export function createReducer<S>(
   ...ons: On<S>[]
 ): ActionReducer<S> {
   const map = new Map<string, ActionReducer<S>>();
-  const devMode = isDevMode();
-
   for (let on of ons) {
     for (let type of on.types) {
-      if (devMode && map.has(type)) {
-        console.warn(
-          `@ngrx/store: The provided action type '${type}' is already provided.`
-        );
-      }
       map.set(type, on.reducer);
     }
   }
+
   return function(state: S = initialState, action: Action): S {
     const reducer = map.get(action.type);
     return reducer ? reducer(state, action) : state;