diff --git a/spec/Subject-spec.js b/spec/Subject-spec.js
index 777a28f9876..dff48247e68 100644
--- a/spec/Subject-spec.js
+++ b/spec/Subject-spec.js
@@ -129,9 +129,6 @@ describe('Subject', function () {
     subscription1.unsubscribe();
 
     subject.complete();
-    subject.next(9);
-    subject.complete();
-    subject.error(new Error('err'));
 
     subscription2.unsubscribe();
 
@@ -179,9 +176,6 @@ describe('Subject', function () {
 
     subscription1.unsubscribe();
 
-    subject.error(new Error('err'));
-    subject.next(9);
-    subject.complete();
     subject.error(new Error('err'));
 
     subscription2.unsubscribe();
@@ -221,9 +215,6 @@ describe('Subject', function () {
     subscription1.unsubscribe();
 
     subject.complete();
-    subject.next(9);
-    subject.complete();
-    subject.error(new Error('err'));
 
     subscription2.unsubscribe();
 
@@ -509,6 +500,57 @@ describe('Subject', function () {
     source.subscribe(subject);
   });
 
+  it('should throw ObjectUnsubscribedError when emit after unsubscribed', function () {
+    var subject = new Rx.Subject();
+    subject.unsubscribe();
+
+    expect(function () {
+      subject.next('a');
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+
+    expect(function () {
+      subject.error('a');
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+
+    expect(function () {
+      subject.complete();
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+  });
+
+  it('should throw ObjectUnsubscribedError when emit after completed', function () {
+    var subject = new Rx.Subject();
+    subject.complete();
+
+    expect(function () {
+      subject.next('a');
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+
+    expect(function () {
+      subject.error('a');
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+
+    expect(function () {
+      subject.complete();
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+  });
+
+  it('should throw ObjectUnsubscribedError when emit after error', function () {
+    var subject = new Rx.Subject();
+    subject.error('e');
+
+    expect(function () {
+      subject.next('a');
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+
+    expect(function () {
+      subject.error('a');
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+
+    expect(function () {
+      subject.complete();
+    }).toThrow(new Rx.ObjectUnsubscribedError());
+  });
+
   describe('asObservable', function () {
     it('should hide subject', function () {
       var subject = new Rx.Subject();
diff --git a/spec/subjects/AsyncSubject-spec.js b/spec/subjects/AsyncSubject-spec.js
index e676114fcab..3c8c65fb4e1 100644
--- a/spec/subjects/AsyncSubject-spec.js
+++ b/spec/subjects/AsyncSubject-spec.js
@@ -70,8 +70,6 @@ describe('AsyncSubject', function () {
     expect(observer.results).toEqual([]);
     subject.complete();
     expect(observer.results).toEqual([2, 'done']);
-    subject.next(3);
-    expect(observer.results).toEqual([2, 'done']);
   });
 
   it('should not emit values if unsubscribed before complete', function () {
diff --git a/src/Subject.ts b/src/Subject.ts
index 315dc6817fa..da8b502cb32 100644
--- a/src/Subject.ts
+++ b/src/Subject.ts
@@ -6,6 +6,9 @@ import {Subscription} from './Subscription';
 import {SubjectSubscription} from './subject/SubjectSubscription';
 import {rxSubscriber} from './symbol/rxSubscriber';
 
+import {throwError} from './util/throwError';
+import {ObjectUnsubscribedError} from './util/ObjectUnsubscribedError';
+
 export class Subject<T> extends Observable<T> implements Observer<T>, Subscription {
 
   static create: Function = <T>(destination: Observer<T>, source: Observable<T>): Subject<T> => {
@@ -53,10 +56,10 @@ export class Subject<T> extends Observable<T> implements Observer<T>, Subscripti
         return subscriber.error(this.errorValue);
       } else if (this.hasCompleted) {
         return subscriber.complete();
-      } else if (this.isUnsubscribed) {
-        throw new Error('Cannot subscribe to a disposed Subject.');
       }
 
+      this.throwIfUnsubscribed();
+
       const subscription = new SubjectSubscription(this, subscriber);
 
       this.observers.push(subscriber);
@@ -73,6 +76,8 @@ export class Subject<T> extends Observable<T> implements Observer<T>, Subscripti
   }
 
   next(value: T): void {
+    this.throwIfUnsubscribed();
+
     if (this.isStopped) {
       return;
     }
@@ -89,6 +94,8 @@ export class Subject<T> extends Observable<T> implements Observer<T>, Subscripti
   }
 
   error(err?: any): void {
+    this.throwIfUnsubscribed();
+
     if (this.isStopped) {
       return;
     }
@@ -105,6 +112,8 @@ export class Subject<T> extends Observable<T> implements Observer<T>, Subscripti
   }
 
   complete(): void {
+    this.throwIfUnsubscribed();
+
     if (this.isStopped) {
       return;
     }
@@ -200,6 +209,12 @@ export class Subject<T> extends Observable<T> implements Observer<T>, Subscripti
     this.unsubscribe();
   }
 
+  private throwIfUnsubscribed(): void {
+    if (this.isUnsubscribed) {
+      throwError(new ObjectUnsubscribedError());
+    }
+  }
+
   [rxSubscriber]() {
     return new Subscriber<T>(this);
   }