diff --git a/examples/drivers/windows/otApi/otApi.cpp b/examples/drivers/windows/otApi/otApi.cpp
index be469e33c..4fa9863db 100644
--- a/examples/drivers/windows/otApi/otApi.cpp
+++ b/examples/drivers/windows/otApi/otApi.cpp
@@ -1316,6 +1316,18 @@ otIsDiscoverInProgress(
     return Result != FALSE;
 }
 
+OTAPI 
+ThreadError
+OTCALL
+otSendMacDataRequest(
+    _In_ otInstance *aInstance
+    )
+{
+    if (aInstance == nullptr) return kThreadError_InvalidArgs;
+    UNREFERENCED_PARAMETER(aInstance);
+    return kThreadError_NotImplemented; // TODO
+}
+
 OTAPI 
 uint8_t 
 OTCALL
diff --git a/include/openthread.h b/include/openthread.h
index e771d166b..fb9726a7c 100644
--- a/include/openthread.h
+++ b/include/openthread.h
@@ -433,6 +433,19 @@ OTAPI ThreadError OTCALL otDiscover(otInstance *aInstance, uint32_t aScanChannel
  */
 OTAPI bool OTCALL otIsDiscoverInProgress(otInstance *aInstance);
 
+/**
+ * This function enqueues an IEEE 802.15.4 Data Request message for transmission.
+ *
+ * @param[in] aInstance  A pointer to an OpenThread instance.
+ *
+ * @retval kThreadError_None          Successfully enqueued an IEEE 802.15.4 Data Request message.
+ * @retval kThreadError_Already       An IEEE 802.15.4 Data Request message is already enqueued.
+ * @retval kThreadError_InvalidState  Device is not in rx-off-when-idle mode.
+ * @retval kThreadError_NoBufs        Insufficient message buffers available.
+ *
+ */
+OTAPI ThreadError OTCALL otSendMacDataRequest(otInstance *aInstance);
+
 /**
  * @}
  *
diff --git a/src/core/openthread.cpp b/src/core/openthread.cpp
index a0cd00f5e..dc97c6cbc 100644
--- a/src/core/openthread.cpp
+++ b/src/core/openthread.cpp
@@ -1376,6 +1376,11 @@ bool otIsDiscoverInProgress(otInstance *aInstance)
     return aInstance->mThreadNetif.GetMle().IsDiscoverInProgress();
 }
 
+ThreadError otSendMacDataRequest(otInstance *aInstance)
+{
+    return aInstance->mThreadNetif.GetMeshForwarder().SendMacDataRequest();
+}
+
 void otSetReceiveIp6DatagramCallback(otInstance *aInstance, otReceiveIp6DatagramCallback aCallback,
                                      void *aCallbackContext)
 {
diff --git a/src/core/thread/mesh_forwarder.cpp b/src/core/thread/mesh_forwarder.cpp
index 97647579c..0d33a3ea2 100644
--- a/src/core/thread/mesh_forwarder.cpp
+++ b/src/core/thread/mesh_forwarder.cpp
@@ -825,15 +825,42 @@ void MeshForwarder::HandlePollTimer(void *aContext)
 
 void MeshForwarder::HandlePollTimer()
 {
+    ThreadError error;
+
+    error = SendMacDataRequest();
+
+    if (error == kThreadError_NoBufs)
+    {
+        mPollTimer.Start(kDataRequstRetryDelay);
+    }
+}
+
+ThreadError MeshForwarder::SendMacDataRequest(void)
+{
+    ThreadError error;
     Message *message;
 
-    if ((message = mNetif.GetIp6().mMessagePool.New(Message::kTypeMacDataPoll, 0)) != NULL)
+    // only send MAC Data Requests in rx-off-when-idle mode
+    VerifyOrExit(!mMac.GetRxOnWhenIdle(), error = kThreadError_InvalidState);
+
+    // only enqueue one MAC Data Request at a time
+    for (message = mSendQueue.GetHead(); message; message = message->GetNext())
     {
-        SendMessage(*message);
-        otLogInfoMac("Sent poll");
+        VerifyOrExit(message->GetType() != Message::kTypeMacDataPoll, error = kThreadError_Already);
     }
 
+    // enqueue a MAC Data Request message
+    message = mNetif.GetIp6().mMessagePool.New(Message::kTypeMacDataPoll, 0);
+    VerifyOrExit(message != NULL, error = kThreadError_NoBufs);
+
+    SuccessOrExit(error = SendMessage(*message));
+    otLogInfoMac("Sent poll");
+
+    // restart the polling timer
     mPollTimer.Start(mPollPeriod);
+
+exit:
+    return error;
 }
 
 ThreadError MeshForwarder::GetMacSourceAddress(const Ip6::Address &aIp6Addr, Mac::Address &aMacAddr)
@@ -947,10 +974,14 @@ exit:
 
 ThreadError MeshForwarder::SendPoll(Message &aMessage, Mac::Frame &aFrame)
 {
+    ThreadError error = kThreadError_None;
     Mac::Address macSource;
     uint16_t fcf;
     Neighbor *neighbor;
 
+    // only send MAC Data Requests in rx-off-when-idle mode
+    VerifyOrExit(!mMac.GetRxOnWhenIdle(), error = kThreadError_InvalidState);
+
     macSource.mShortAddress = mMac.GetShortAddress();
 
     if (macSource.mShortAddress != Mac::kShortAddrInvalid)
@@ -998,7 +1029,8 @@ ThreadError MeshForwarder::SendPoll(Message &aMessage, Mac::Frame &aFrame)
 
     mMessageNextOffset = aMessage.GetLength();
 
-    return kThreadError_None;
+exit:
+    return error;
 }
 
 ThreadError MeshForwarder::SendMesh(Message &aMessage, Mac::Frame &aFrame)
diff --git a/src/core/thread/mesh_forwarder.hpp b/src/core/thread/mesh_forwarder.hpp
index 73d541c01..06ccc592f 100644
--- a/src/core/thread/mesh_forwarder.hpp
+++ b/src/core/thread/mesh_forwarder.hpp
@@ -154,6 +154,17 @@ public:
      */
     void SetPollPeriod(uint32_t aPeriod);
 
+    /**
+     * This method enqueues an IEEE 802.15.4 Data Request message.
+     *
+     * @retval kThreadError_None          Successfully enqueued an IEEE 802.15.4 Data Request message.
+     * @retval kThreadError_Already       An IEEE 802.15.4 Data Request message is already enqueued.
+     * @retval kThreadError_InvalidState  Device is not in rx-off-when-idle mode.
+     * @retval kThreadError_NoBufs        Insufficient message buffers available.
+     *
+     */
+    ThreadError SendMacDataRequest(void);
+
     /**
      * This method gets the Data Poll period.
      *
@@ -204,7 +215,8 @@ public:
 private:
     enum
     {
-        kStateUpdatePeriod = 1000,  ///< State update period in milliseconds.
+        kStateUpdatePeriod    = 1000,  ///< State update period in milliseconds.
+        kDataRequstRetryDelay = 1000,  ///< Retry delay in milliseconds.
     };
 
     ThreadError CheckReachability(uint8_t *aFrame, uint8_t aFrameLength,