diff --git a/kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/Deferred.kt b/kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/Deferred.kt
index c9c3582..ab61173 100644
--- a/kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/Deferred.kt
+++ b/kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/Deferred.kt
@@ -23,9 +23,34 @@
  * Deferred value is conceptually a non-blocking cancellable future.
  * It is created with [defer] coroutine builder.
  * It is in [active][isActive] state while the value is being computed.
+ *
+ * Deferred value has four states:
+ *
+ * * _Active_ (initial state) -- [isActive] `true`, [isCompletedExceptionally] `false`,
+ *   and [isCancelled] `false`.
+ *   Both [getCompleted] and [getCompletionException] throw [IllegalStateException].
+ * * _Computed_ (final _completed_ state) -- [isActive] `false`,
+ *   [isCompletedExceptionally] `false`, [isCancelled] `false`.
+ * * _Failed_ (final _completed_ state) -- [isActive] `false`,
+ *   [isCompletedExceptionally] `true`, [isCancelled] `false`.
+ * * _Canceled_ (final _completed_ state) -- [isActive] `false`,
+ *   [isCompletedExceptionally] `true`, [isCancelled] `true`.
  */
 public interface Deferred<out T> : Job {
     /**
+     * Returns `true` if computation of this deferred value has _completed exceptionally_ -- it had
+     * either _failed_ with exception during computation or was [cancelled][cancel].
+     * It implies that [isActive] is `false`.
+     */
+    val isCompletedExceptionally: Boolean
+
+    /**
+     * Returns `true` if computation of this deferred value was [cancelled][cancel].
+     * It implies that [isActive] is `false` and [isCompletedExceptionally] is `true`.
+     */
+    val isCancelled: Boolean
+
+    /**
      * Awaits for completion of this value without blocking a thread and resumes when deferred computation is complete.
      * This suspending function is cancellable.
      * If the [Job] of the current coroutine is completed while this suspending function is waiting, this function
@@ -62,6 +87,9 @@
 ) : AbstractCoroutine<T>(context), Deferred<T> {
     protected open fun start(): Boolean = false // LazyDeferredCoroutine overrides
 
+    override val isCompletedExceptionally: Boolean get() = getState() is CompletedExceptionally
+    override val isCancelled: Boolean get() = getState() is Cancelled
+
     @Suppress("UNCHECKED_CAST")
     suspend override fun await(): T {
         // quick check if already complete (avoid extra object creation)