diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapFutureSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapAsyncSpec.scala
similarity index 87%
rename from akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapFutureSpec.scala
rename to akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapAsyncSpec.scala
index 316839aa58..e95fb96006 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapFutureSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapAsyncSpec.scala
@@ -14,16 +14,16 @@ import scala.concurrent.Await
 import scala.concurrent.Future
 
 @org.junit.runner.RunWith(classOf[org.scalatest.junit.JUnitRunner])
-class FlowMapFutureSpec extends AkkaSpec {
+class FlowMapAsyncSpec extends AkkaSpec {
 
   implicit val materializer = FlowMaterializer()
 
-  "A Flow with mapFuture" must {
+  "A Flow with mapAsync" must {
 
     "produce future elements" in {
       val c = StreamTestKit.SubscriberProbe[Int]()
       implicit val ec = system.dispatcher
-      val p = FlowFrom(1 to 3).mapFuture(n ⇒ Future(n)).publishTo(c)
+      val p = FlowFrom(1 to 3).mapAsync(n ⇒ Future(n)).publishTo(c)
       val sub = c.expectSubscription()
       sub.request(2)
       c.expectNext(1)
@@ -37,7 +37,7 @@ class FlowMapFutureSpec extends AkkaSpec {
     "produce future elements in order" in {
       val c = StreamTestKit.SubscriberProbe[Int]()
       implicit val ec = system.dispatcher
-      val p = FlowFrom(1 to 50).mapFuture(n ⇒ Future {
+      val p = FlowFrom(1 to 50).mapAsync(n ⇒ Future {
         Thread.sleep(ThreadLocalRandom.current().nextInt(1, 10))
         n
       }).publishTo(c)
@@ -51,7 +51,7 @@ class FlowMapFutureSpec extends AkkaSpec {
       val probe = TestProbe()
       val c = StreamTestKit.SubscriberProbe[Int]()
       implicit val ec = system.dispatcher
-      val p = FlowFrom(1 to 20).mapFuture(n ⇒ Future {
+      val p = FlowFrom(1 to 20).mapAsync(n ⇒ Future {
         probe.ref ! n
         n
       }).publishTo(c)
@@ -76,7 +76,7 @@ class FlowMapFutureSpec extends AkkaSpec {
       val latch = TestLatch(1)
       val c = StreamTestKit.SubscriberProbe[Int]()
       implicit val ec = system.dispatcher
-      val p = FlowFrom(1 to 5).mapFuture(n ⇒ Future {
+      val p = FlowFrom(1 to 5).mapAsync(n ⇒ Future {
         if (n == 3) throw new RuntimeException("err1") with NoStackTrace
         else {
           Await.ready(latch, 10.seconds)
@@ -89,11 +89,11 @@ class FlowMapFutureSpec extends AkkaSpec {
       latch.countDown()
     }
 
-    "signal error from mapFuture" in {
+    "signal error from mapAsync" in {
       val latch = TestLatch(1)
       val c = StreamTestKit.SubscriberProbe[Int]()
       implicit val ec = system.dispatcher
-      val p = FlowFrom(1 to 5).mapFuture(n ⇒
+      val p = FlowFrom(1 to 5).mapAsync(n ⇒
         if (n == 3) throw new RuntimeException("err2") with NoStackTrace
         else {
           Future {
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapAsyncUnorderedSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapAsyncUnorderedSpec.scala
new file mode 100644
index 0000000000..d408511901
--- /dev/null
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl2/FlowMapAsyncUnorderedSpec.scala
@@ -0,0 +1,106 @@
+/**
+ * Copyright (C) 2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.stream.scaladsl2
+
+import scala.concurrent.duration._
+import scala.concurrent.forkjoin.ThreadLocalRandom
+import scala.util.control.NoStackTrace
+import akka.stream.testkit.AkkaSpec
+import akka.stream.testkit.StreamTestKit
+import akka.testkit.TestProbe
+import akka.testkit.TestLatch
+import scala.concurrent.Await
+import scala.concurrent.Future
+
+class FlowMapAsyncUnorderedSpec extends AkkaSpec {
+
+  implicit val materializer = FlowMaterializer()
+
+  "A Flow with mapAsyncUnordered" must {
+
+    "produce future elements in the order they are ready" in {
+      val c = StreamTestKit.SubscriberProbe[Int]()
+      implicit val ec = system.dispatcher
+      val latch = (1 to 4).map(_ -> TestLatch(1)).toMap
+      val p = FlowFrom(1 to 4).mapAsyncUnordered(n ⇒ Future {
+        Await.ready(latch(n), 5.seconds)
+        n
+      }).publishTo(c)
+      val sub = c.expectSubscription()
+      sub.request(5)
+      latch(2).countDown()
+      c.expectNext(2)
+      latch(4).countDown()
+      c.expectNext(4)
+      latch(3).countDown()
+      c.expectNext(3)
+      latch(1).countDown()
+      c.expectNext(1)
+      c.expectComplete()
+    }
+
+    "not run more futures than requested elements" in {
+      val probe = TestProbe()
+      val c = StreamTestKit.SubscriberProbe[Int]()
+      implicit val ec = system.dispatcher
+      val p = FlowFrom(1 to 20).mapAsyncUnordered(n ⇒ Future {
+        probe.ref ! n
+        n
+      }).publishTo(c)
+      val sub = c.expectSubscription()
+      // nothing before requested
+      probe.expectNoMsg(500.millis)
+      sub.request(1)
+      val elem1 = probe.expectMsgType[Int]
+      probe.expectNoMsg(500.millis)
+      sub.request(2)
+      val elem2 = probe.expectMsgType[Int]
+      val elem3 = probe.expectMsgType[Int]
+      probe.expectNoMsg(500.millis)
+      sub.request(100)
+      (probe.receiveN(17).toSet + elem1 + elem2 + elem3) should be((1 to 20).toSet)
+      probe.expectNoMsg(200.millis)
+
+      c.probe.receiveN(20).toSet should be((1 to 20).map(StreamTestKit.OnNext.apply).toSet)
+      c.expectComplete()
+    }
+
+    "signal future failure" in {
+      val latch = TestLatch(1)
+      val c = StreamTestKit.SubscriberProbe[Int]()
+      implicit val ec = system.dispatcher
+      val p = FlowFrom(1 to 5).mapAsyncUnordered(n ⇒ Future {
+        if (n == 3) throw new RuntimeException("err1") with NoStackTrace
+        else {
+          Await.ready(latch, 10.seconds)
+          n
+        }
+      }).publishTo(c)
+      val sub = c.expectSubscription()
+      sub.request(10)
+      c.expectError.getMessage should be("err1")
+      latch.countDown()
+    }
+
+    "signal error from mapAsyncUnordered" in {
+      val latch = TestLatch(1)
+      val c = StreamTestKit.SubscriberProbe[Int]()
+      implicit val ec = system.dispatcher
+      val p = FlowFrom(1 to 5).mapAsync(n ⇒
+        if (n == 3) throw new RuntimeException("err2") with NoStackTrace
+        else {
+          Future {
+            Await.ready(latch, 10.seconds)
+            n
+          }
+        }).
+        publishTo(c)
+      val sub = c.expectSubscription()
+      sub.request(10)
+      c.expectError.getMessage should be("err2")
+      latch.countDown()
+    }
+
+  }
+}
diff --git a/akka-stream/src/main/scala/akka/stream/impl/ActorProcessor.scala b/akka-stream/src/main/scala/akka/stream/impl/ActorProcessor.scala
index a81fe87e0b..b5cf030242 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/ActorProcessor.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/ActorProcessor.scala
@@ -32,7 +32,7 @@ private[akka] object ActorProcessor {
       case bf: Buffer        ⇒ Props(new BufferImpl(settings, bf.size, bf.overflowStrategy))
       case tt: PrefixAndTail ⇒ Props(new PrefixAndTailImpl(settings, tt.n))
       case ConcatAll         ⇒ Props(new ConcatAllImpl(settings))
-      case m: MapFuture      ⇒ Props(new MapFutureProcessorImpl(settings, m.f))
+      case m: MapFuture      ⇒ Props(new MapAsyncProcessorImpl(settings, m.f))
     }).withDispatcher(settings.dispatcher)
 
   def apply[I, O](impl: ActorRef): ActorProcessor[I, O] = {
diff --git a/akka-stream/src/main/scala/akka/stream/impl/Emit.scala b/akka-stream/src/main/scala/akka/stream/impl/Emit.scala
new file mode 100644
index 0000000000..f757d6910e
--- /dev/null
+++ b/akka-stream/src/main/scala/akka/stream/impl/Emit.scala
@@ -0,0 +1,33 @@
+/**
+ * Copyright (C) 2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.stream.impl
+
+import scala.collection.immutable
+
+/**
+ * INTERNAL API
+ */
+private[akka] trait Emit { this: ActorProcessorImpl with Pump ⇒
+
+  // TODO performance improvement: mutable buffer?
+  var emits = immutable.Seq.empty[Any]
+
+  // Save previous phase we should return to in a var to avoid allocation
+  private var phaseAfterFlush: TransferPhase = _
+
+  // Enters flushing phase if there are emits pending
+  def emitAndThen(andThen: TransferPhase): Unit =
+    if (emits.nonEmpty) {
+      phaseAfterFlush = andThen
+      nextPhase(emitting)
+    } else nextPhase(andThen)
+
+  // Emits all pending elements, then returns to savedPhase
+  private val emitting = TransferPhase(primaryOutputs.NeedsDemand) { () ⇒
+    primaryOutputs.enqueueOutputElement(emits.head)
+    emits = emits.tail
+    if (emits.isEmpty) nextPhase(phaseAfterFlush)
+  }
+
+}
diff --git a/akka-stream/src/main/scala/akka/stream/impl/MapFutureProcessorImpl.scala b/akka-stream/src/main/scala/akka/stream/impl/MapAsyncProcessorImpl.scala
similarity index 80%
rename from akka-stream/src/main/scala/akka/stream/impl/MapFutureProcessorImpl.scala
rename to akka-stream/src/main/scala/akka/stream/impl/MapAsyncProcessorImpl.scala
index 37e7aaa3e1..3e62562db2 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/MapFutureProcessorImpl.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/MapAsyncProcessorImpl.scala
@@ -15,7 +15,7 @@ import scala.annotation.tailrec
 /**
  * INTERNAL API
  */
-private[akka] object MapFutureProcessorImpl {
+private[akka] object MapAsyncProcessorImpl {
 
   object FutureElement {
     implicit val ordering: Ordering[FutureElement] = new Ordering[FutureElement] {
@@ -32,15 +32,13 @@ private[akka] object MapFutureProcessorImpl {
 /**
  * INTERNAL API
  */
-private[akka] class MapFutureProcessorImpl(_settings: MaterializerSettings, f: Any ⇒ Future[Any]) extends ActorProcessorImpl(_settings) {
-  import MapFutureProcessorImpl._
+private[akka] class MapAsyncProcessorImpl(_settings: MaterializerSettings, f: Any ⇒ Future[Any])
+  extends ActorProcessorImpl(_settings) with Emit {
+  import MapAsyncProcessorImpl._
 
   // Execution context for pipeTo and friends
   import context.dispatcher
 
-  // TODO performance improvement: mutable buffer?
-  var emits = immutable.Seq.empty[Any]
-
   var submittedSeqNo = 0L
   var doneSeqNo = 0L
   def gap: Long = submittedSeqNo - doneSeqNo
@@ -134,23 +132,6 @@ private[akka] class MapFutureProcessorImpl(_settings: MaterializerSettings, f: A
     }
   }
 
-  // Save previous phase we should return to in a var to avoid allocation
-  var phaseAfterFlush: TransferPhase = _
-
-  // Enters flushing phase if there are emits pending
-  def emitAndThen(andThen: TransferPhase): Unit =
-    if (emits.nonEmpty) {
-      phaseAfterFlush = andThen
-      nextPhase(emitting)
-    } else nextPhase(andThen)
-
-  // Emits all pending elements, then returns to savedPhase
-  val emitting = TransferPhase(primaryOutputs.NeedsDemand) { () ⇒
-    primaryOutputs.enqueueOutputElement(emits.head)
-    emits = emits.tail
-    if (emits.isEmpty) nextPhase(phaseAfterFlush)
-  }
-
   nextPhase(running)
 
 }
diff --git a/akka-stream/src/main/scala/akka/stream/impl/SingleStreamProcessors.scala b/akka-stream/src/main/scala/akka/stream/impl/SingleStreamProcessors.scala
index a9bb2555ed..c1eb21f90d 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/SingleStreamProcessors.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/SingleStreamProcessors.scala
@@ -13,10 +13,8 @@ import scala.util.control.NonFatal
  * INTERNAL API
  */
 private[akka] class TransformProcessorImpl(_settings: MaterializerSettings, transformer: TransformerLike[Any, Any])
-  extends ActorProcessorImpl(_settings) {
+  extends ActorProcessorImpl(_settings) with Emit {
 
-  // TODO performance improvement: mutable buffer?
-  var emits = immutable.Seq.empty[Any]
   var errorEvent: Option[Throwable] = None
 
   override def preStart(): Unit = {
@@ -53,23 +51,6 @@ private[akka] class TransformProcessorImpl(_settings: MaterializerSettings, tran
     emitAndThen(completedPhase)
   }
 
-  // Save previous phase we should return to in a var to avoid allocation
-  var phaseAfterFlush: TransferPhase = _
-
-  // Enters flushing phase if there are emits pending
-  def emitAndThen(andThen: TransferPhase): Unit =
-    if (emits.nonEmpty) {
-      phaseAfterFlush = andThen
-      nextPhase(emitting)
-    } else nextPhase(andThen)
-
-  // Emits all pending elements, then returns to savedPhase
-  val emitting = TransferPhase(primaryOutputs.NeedsDemand) { () ⇒
-    primaryOutputs.enqueueOutputElement(emits.head)
-    emits = emits.tail
-    if (emits.isEmpty) nextPhase(phaseAfterFlush)
-  }
-
   override def toString: String = s"Transformer(emits=$emits, transformer=$transformer)"
 
   override def postStop(): Unit = try super.postStop() finally transformer.cleanup()
diff --git a/akka-stream/src/main/scala/akka/stream/impl2/ActorBasedFlowMaterializer.scala b/akka-stream/src/main/scala/akka/stream/impl2/ActorBasedFlowMaterializer.scala
index 6bf7f6aabf..6a7347866b 100644
--- a/akka-stream/src/main/scala/akka/stream/impl2/ActorBasedFlowMaterializer.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl2/ActorBasedFlowMaterializer.scala
@@ -23,7 +23,7 @@ import akka.stream.impl.ConflateImpl
 import akka.stream.impl.ExpandImpl
 import akka.stream.impl.BufferImpl
 import akka.stream.impl.BlackholeSubscriber
-import akka.stream.impl.MapFutureProcessorImpl
+import akka.stream.impl.MapAsyncProcessorImpl
 
 /**
  * INTERNAL API
@@ -37,8 +37,12 @@ private[akka] object Ast {
 
   case class TimerTransform(name: String, mkTransformer: () ⇒ TimerTransformer[Any, Any]) extends AstNode
 
-  case class MapFuture(f: Any ⇒ Future[Any]) extends AstNode {
-    override def name = "mapFuture"
+  case class MapAsync(f: Any ⇒ Future[Any]) extends AstNode {
+    override def name = "mapAsync"
+  }
+
+  case class MapAsyncUnordered(f: Any ⇒ Future[Any]) extends AstNode {
+    override def name = "mapAsyncUnordered"
   }
 
   case class GroupBy(f: Any ⇒ Any) extends AstNode {
@@ -290,16 +294,17 @@ private[akka] object ActorProcessorFactory {
   def props(materializer: FlowMaterializer, op: AstNode): Props = {
     val settings = materializer.settings
     (op match {
-      case t: Transform      ⇒ Props(new TransformProcessorImpl(settings, t.mkTransformer()))
-      case t: TimerTransform ⇒ Props(new TimerTransformerProcessorsImpl(settings, t.mkTransformer()))
-      case m: MapFuture      ⇒ Props(new MapFutureProcessorImpl(settings, m.f))
-      case g: GroupBy        ⇒ Props(new GroupByProcessorImpl(settings, g.f))
-      case tt: PrefixAndTail ⇒ Props(new PrefixAndTailImpl(settings, tt.n))
-      case s: SplitWhen      ⇒ Props(new SplitWhenProcessorImpl(settings, s.p))
-      case ConcatAll         ⇒ Props(new ConcatAllImpl(materializer))
-      case cf: Conflate      ⇒ Props(new ConflateImpl(settings, cf.seed, cf.aggregate))
-      case ex: Expand        ⇒ Props(new ExpandImpl(settings, ex.seed, ex.extrapolate))
-      case bf: Buffer        ⇒ Props(new BufferImpl(settings, bf.size, bf.overflowStrategy))
+      case t: Transform         ⇒ Props(new TransformProcessorImpl(settings, t.mkTransformer()))
+      case t: TimerTransform    ⇒ Props(new TimerTransformerProcessorsImpl(settings, t.mkTransformer()))
+      case m: MapAsync          ⇒ Props(new MapAsyncProcessorImpl(settings, m.f))
+      case m: MapAsyncUnordered ⇒ Props(new MapAsyncUnorderedProcessorImpl(settings, m.f))
+      case g: GroupBy           ⇒ Props(new GroupByProcessorImpl(settings, g.f))
+      case tt: PrefixAndTail    ⇒ Props(new PrefixAndTailImpl(settings, tt.n))
+      case s: SplitWhen         ⇒ Props(new SplitWhenProcessorImpl(settings, s.p))
+      case ConcatAll            ⇒ Props(new ConcatAllImpl(materializer))
+      case cf: Conflate         ⇒ Props(new ConflateImpl(settings, cf.seed, cf.aggregate))
+      case ex: Expand           ⇒ Props(new ExpandImpl(settings, ex.seed, ex.extrapolate))
+      case bf: Buffer           ⇒ Props(new BufferImpl(settings, bf.size, bf.overflowStrategy))
     }).withDispatcher(settings.dispatcher)
   }
 
diff --git a/akka-stream/src/main/scala/akka/stream/impl2/MapAsyncUnorderedProcessorImpl.scala b/akka-stream/src/main/scala/akka/stream/impl2/MapAsyncUnorderedProcessorImpl.scala
new file mode 100644
index 0000000000..3a52a5296d
--- /dev/null
+++ b/akka-stream/src/main/scala/akka/stream/impl2/MapAsyncUnorderedProcessorImpl.scala
@@ -0,0 +1,81 @@
+/**
+ * Copyright (C) 2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.stream.impl2
+
+import scala.collection.immutable
+import scala.concurrent.Future
+import scala.util.control.NonFatal
+import akka.stream.MaterializerSettings
+import akka.stream.impl.ActorProcessorImpl
+import akka.stream.impl.Emit
+import akka.stream.impl.TransferPhase
+import akka.stream.impl.TransferState
+import akka.pattern.pipe
+
+/**
+ * INTERNAL API
+ */
+private[akka] object MapAsyncUnorderedProcessorImpl {
+  case class FutureElement(element: Any)
+  case class FutureFailure(cause: Throwable)
+}
+
+/**
+ * INTERNAL API
+ */
+private[akka] class MapAsyncUnorderedProcessorImpl(_settings: MaterializerSettings, f: Any ⇒ Future[Any])
+  extends ActorProcessorImpl(_settings) with Emit {
+  import MapAsyncUnorderedProcessorImpl._
+
+  // Execution context for pipeTo and friends
+  import context.dispatcher
+
+  var inProgressCount = 0
+
+  override def activeReceive = futureReceive orElse super.activeReceive
+
+  def futureReceive: Receive = {
+    case FutureElement(element) ⇒
+      inProgressCount -= 1
+      emits = List(element)
+      emitAndThen(running)
+      pump()
+
+    case FutureFailure(cause) ⇒
+      fail(cause)
+  }
+
+  override def onError(e: Throwable): Unit = {
+    // propagate upstream error immediately
+    fail(e)
+  }
+
+  object RunningPhaseCondition extends TransferState {
+    def isReady = (primaryInputs.inputsAvailable && primaryOutputs.demandCount - inProgressCount > 0) ||
+      (primaryInputs.inputsDepleted && inProgressCount == 0)
+    def isCompleted = false
+  }
+
+  val running: TransferPhase = TransferPhase(RunningPhaseCondition) { () ⇒
+    if (primaryInputs.inputsDepleted) {
+      emitAndThen(completedPhase)
+    } else if (primaryInputs.inputsAvailable && primaryOutputs.demandCount - inProgressCount > 0) {
+      val elem = primaryInputs.dequeueInputElement()
+      inProgressCount += 1
+      try {
+        f(elem).map(FutureElement.apply).recover {
+          case err ⇒ FutureFailure(err)
+        }.pipeTo(self)
+      } catch {
+        case NonFatal(err) ⇒
+          // f threw, propagate error immediately
+          fail(err)
+      }
+      emitAndThen(running)
+    }
+  }
+
+  nextPhase(running)
+
+}
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl2/Flow.scala b/akka-stream/src/main/scala/akka/stream/scaladsl2/Flow.scala
index a7d182f25e..8cf2a6237f 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl2/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl2/Flow.scala
@@ -73,9 +73,24 @@ trait FlowOps[-In, +Out] {
    * element that will be emitted downstream. As many futures as requested elements by
    * downstream may run in parallel and may complete in any order, but the elements that
    * are emitted downstream are in the same order as from upstream.
+   *
+   * @see [[#mapAsyncUnordered]]
    */
-  def mapFuture[T](f: Out ⇒ Future[T]): Repr[In, T] =
-    andThen(MapFuture(f.asInstanceOf[Any ⇒ Future[Any]]))
+  def mapAsync[T](f: Out ⇒ Future[T]): Repr[In, T] =
+    andThen(MapAsync(f.asInstanceOf[Any ⇒ Future[Any]]))
+
+  /**
+   * Transform this stream by applying the given function to each of the elements
+   * as they pass through this processing step. The function returns a `Future` of the
+   * element that will be emitted downstream. As many futures as requested elements by
+   * downstream may run in parallel and each processed element will be emitted dowstream
+   * as soon as it is ready, i.e. it is possible that the elements are not emitted downstream
+   * in the same order as from upstream.
+   *
+   * @see [[#mapAsync]]
+   */
+  def mapAsyncUnordered[T](f: Out ⇒ Future[T]): Repr[In, T] =
+    andThen(MapAsyncUnordered(f.asInstanceOf[Any ⇒ Future[Any]]))
 
   /**
    * Only pass on those elements that satisfy the given predicate.