diff --git a/call/rtp_transport_controller_send_interface.h b/call/rtp_transport_controller_send_interface.h
index d564035..450b65b 100644
--- a/call/rtp_transport_controller_send_interface.h
+++ b/call/rtp_transport_controller_send_interface.h
@@ -54,6 +54,7 @@
 struct RtpSenderObservers {
   RtcpRttStats* rtcp_rtt_stats;
   RtcpIntraFrameObserver* intra_frame_callback;
+  RtcpLossNotificationObserver* rtcp_loss_notification_observer;
   RtcpStatisticsCallback* rtcp_stats;
   StreamDataCountersCallback* rtp_stats;
   BitrateStatisticsObserver* bitrate_observer;
diff --git a/call/rtp_video_sender.cc b/call/rtp_video_sender.cc
index 98cdd9a..94a8fad 100644
--- a/call/rtp_video_sender.cc
+++ b/call/rtp_video_sender.cc
@@ -63,6 +63,7 @@
     int rtcp_report_interval_ms,
     Transport* send_transport,
     RtcpIntraFrameObserver* intra_frame_callback,
+    RtcpLossNotificationObserver* rtcp_loss_notification_observer,
     RtcpBandwidthObserver* bandwidth_callback,
     RtpTransportControllerSendInterface* transport,
     RtcpRttStats* rtt_stats,
@@ -84,6 +85,8 @@
   configuration.receiver_only = false;
   configuration.outgoing_transport = send_transport;
   configuration.intra_frame_callback = intra_frame_callback;
+  configuration.rtcp_loss_notification_observer =
+      rtcp_loss_notification_observer;
   configuration.bandwidth_callback = bandwidth_callback;
   configuration.transport_feedback_callback =
       transport->transport_feedback_observer();
@@ -228,24 +231,26 @@
       flexfec_sender_(
           MaybeCreateFlexfecSender(clock, rtp_config, suspended_ssrcs_)),
       fec_controller_(std::move(fec_controller)),
-      rtp_streams_(CreateRtpStreamSenders(clock,
-                                          rtp_config,
-                                          rtcp_report_interval_ms,
-                                          send_transport,
-                                          observers.intra_frame_callback,
-                                          transport->GetBandwidthObserver(),
-                                          transport,
-                                          observers.rtcp_rtt_stats,
-                                          flexfec_sender_.get(),
-                                          observers.bitrate_observer,
-                                          observers.rtcp_type_observer,
-                                          observers.send_delay_observer,
-                                          observers.send_packet_observer,
-                                          event_log,
-                                          retransmission_limiter,
-                                          this,
-                                          frame_encryptor,
-                                          crypto_options)),
+      rtp_streams_(
+          CreateRtpStreamSenders(clock,
+                                 rtp_config,
+                                 rtcp_report_interval_ms,
+                                 send_transport,
+                                 observers.intra_frame_callback,
+                                 observers.rtcp_loss_notification_observer,
+                                 transport->GetBandwidthObserver(),
+                                 transport,
+                                 observers.rtcp_rtt_stats,
+                                 flexfec_sender_.get(),
+                                 observers.bitrate_observer,
+                                 observers.rtcp_type_observer,
+                                 observers.send_delay_observer,
+                                 observers.send_packet_observer,
+                                 event_log,
+                                 retransmission_limiter,
+                                 this,
+                                 frame_encryptor,
+                                 crypto_options)),
       rtp_config_(rtp_config),
       transport_(transport),
       transport_overhead_bytes_per_packet_(0),
diff --git a/modules/rtp_rtcp/include/rtp_rtcp.h b/modules/rtp_rtcp/include/rtp_rtcp.h
index 9ae6ddb..1c589f4 100644
--- a/modules/rtp_rtcp/include/rtp_rtcp.h
+++ b/modules/rtp_rtcp/include/rtp_rtcp.h
@@ -64,9 +64,12 @@
     // out on the network.
     Transport* outgoing_transport = nullptr;
 
-    // Called when the receiver request a intra frame.
+    // Called when the receiver requests an intra frame.
     RtcpIntraFrameObserver* intra_frame_callback = nullptr;
 
+    // Called when the receiver sends a loss notification.
+    RtcpLossNotificationObserver* rtcp_loss_notification_observer = nullptr;
+
     // Called when we receive a changed estimate from the receiver of out
     // stream.
     RtcpBandwidthObserver* bandwidth_callback = nullptr;
diff --git a/modules/rtp_rtcp/include/rtp_rtcp_defines.h b/modules/rtp_rtcp/include/rtp_rtcp_defines.h
index cbeb77f..41ab1cf 100644
--- a/modules/rtp_rtcp/include/rtp_rtcp_defines.h
+++ b/modules/rtp_rtcp/include/rtp_rtcp_defines.h
@@ -186,6 +186,18 @@
   virtual void OnReceivedIntraFrameRequest(uint32_t ssrc) = 0;
 };
 
+// Observer for incoming LossNotification RTCP messages.
+// See the documentation of LossNotification for details.
+class RtcpLossNotificationObserver {
+ public:
+  virtual ~RtcpLossNotificationObserver() = default;
+
+  virtual void OnReceivedLossNotification(uint32_t ssrc,
+                                          uint16_t seq_num_of_last_decodable,
+                                          uint16_t seq_num_of_last_received,
+                                          bool decodability_flag) = 0;
+};
+
 class RtcpBandwidthObserver {
  public:
   // REMB or TMMBR
diff --git a/modules/rtp_rtcp/source/rtcp_receiver.cc b/modules/rtp_rtcp/source/rtcp_receiver.cc
index e3b1d13..0c1c326 100644
--- a/modules/rtp_rtcp/source/rtcp_receiver.cc
+++ b/modules/rtp_rtcp/source/rtcp_receiver.cc
@@ -131,6 +131,7 @@
     RtcpPacketTypeCounterObserver* packet_type_counter_observer,
     RtcpBandwidthObserver* rtcp_bandwidth_observer,
     RtcpIntraFrameObserver* rtcp_intra_frame_observer,
+    RtcpLossNotificationObserver* rtcp_loss_notification_observer,
     TransportFeedbackObserver* transport_feedback_observer,
     VideoBitrateAllocationObserver* bitrate_allocation_observer,
     int report_interval_ms,
@@ -140,6 +141,7 @@
       rtp_rtcp_(owner),
       rtcp_bandwidth_observer_(rtcp_bandwidth_observer),
       rtcp_intra_frame_observer_(rtcp_intra_frame_observer),
+      rtcp_loss_notification_observer_(rtcp_loss_notification_observer),
       transport_feedback_observer_(transport_feedback_observer),
       bitrate_allocation_observer_(bitrate_allocation_observer),
       report_interval_ms_(report_interval_ms),
@@ -1019,6 +1021,18 @@
       rtcp_intra_frame_observer_->OnReceivedIntraFrameRequest(local_ssrc);
     }
   }
+  if (rtcp_loss_notification_observer_ &&
+      (packet_information.packet_type_flags & kRtcpLossNotification)) {
+    rtcp::LossNotification* loss_notification =
+        packet_information.loss_notification.get();
+    RTC_DCHECK(loss_notification);
+    if (loss_notification->media_ssrc() == local_ssrc) {
+      rtcp_loss_notification_observer_->OnReceivedLossNotification(
+          loss_notification->media_ssrc(), loss_notification->last_decoded(),
+          loss_notification->last_received(),
+          loss_notification->decodability_flag());
+    }
+  }
   if (rtcp_bandwidth_observer_) {
     RTC_DCHECK(!receiver_only_);
     if (packet_information.packet_type_flags & kRtcpRemb) {
@@ -1028,16 +1042,6 @@
       rtcp_bandwidth_observer_->OnReceivedEstimatedBitrate(
           packet_information.receiver_estimated_max_bitrate_bps);
     }
-    if (packet_information.packet_type_flags & kRtcpLossNotification) {
-      rtcp::LossNotification* loss_notification =
-          packet_information.loss_notification.get();
-      RTC_DCHECK(loss_notification);
-      RTC_LOG(LS_VERBOSE) << "Incoming Loss Notification: ("
-                          << loss_notification->last_decoded() << ", "
-                          << loss_notification->last_received() << ", "
-                          << loss_notification->decodability_flag() << ").";
-      // TODO(eladalon): Notify observer.
-    }
     if ((packet_information.packet_type_flags & kRtcpSr) ||
         (packet_information.packet_type_flags & kRtcpRr)) {
       int64_t now_ms = clock_->TimeInMilliseconds();
diff --git a/modules/rtp_rtcp/source/rtcp_receiver.h b/modules/rtp_rtcp/source/rtcp_receiver.h
index fe6ec4c..afc3f96 100644
--- a/modules/rtp_rtcp/source/rtcp_receiver.h
+++ b/modules/rtp_rtcp/source/rtcp_receiver.h
@@ -55,6 +55,7 @@
                RtcpPacketTypeCounterObserver* packet_type_counter_observer,
                RtcpBandwidthObserver* rtcp_bandwidth_observer,
                RtcpIntraFrameObserver* rtcp_intra_frame_observer,
+               RtcpLossNotificationObserver* rtcp_loss_notification_observer,
                TransportFeedbackObserver* transport_feedback_observer,
                VideoBitrateAllocationObserver* bitrate_allocation_observer,
                int report_interval_ms,
@@ -215,6 +216,7 @@
   rtc::CriticalSection feedbacks_lock_;
   RtcpBandwidthObserver* const rtcp_bandwidth_observer_;
   RtcpIntraFrameObserver* const rtcp_intra_frame_observer_;
+  RtcpLossNotificationObserver* const rtcp_loss_notification_observer_;
   TransportFeedbackObserver* const transport_feedback_observer_;
   VideoBitrateAllocationObserver* const bitrate_allocation_observer_;
   const int report_interval_ms_;
diff --git a/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc b/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
index 10351da..e1483a4 100644
--- a/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
+++ b/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
@@ -66,6 +66,16 @@
   MOCK_METHOD1(OnReceivedIntraFrameRequest, void(uint32_t));
 };
 
+class MockRtcpLossNotificationObserver : public RtcpLossNotificationObserver {
+ public:
+  ~MockRtcpLossNotificationObserver() override = default;
+  MOCK_METHOD4(OnReceivedLossNotification,
+               void(uint32_t ssrc,
+                    uint16_t seq_num_of_last_decodable,
+                    uint16_t seq_num_of_last_received,
+                    bool decodability_flag));
+};
+
 class MockRtcpCallbackImpl : public RtcpStatisticsCallback {
  public:
   MOCK_METHOD2(StatisticsUpdated, void(const RtcpStatistics&, uint32_t));
@@ -119,6 +129,7 @@
                        &packet_type_counter_observer_,
                        &bandwidth_observer_,
                        &intra_frame_observer_,
+                       &rtcp_loss_notification_observer_,
                        &transport_feedback_observer_,
                        &bitrate_allocation_observer_,
                        kRtcpIntervalMs,
@@ -145,6 +156,7 @@
   NiceMock<MockRtcpPacketTypeCounterObserver> packet_type_counter_observer_;
   StrictMock<MockRtcpBandwidthObserver> bandwidth_observer_;
   StrictMock<MockRtcpIntraFrameObserver> intra_frame_observer_;
+  StrictMock<MockRtcpLossNotificationObserver> rtcp_loss_notification_observer_;
   StrictMock<MockTransportFeedbackObserver> transport_feedback_observer_;
   StrictMock<MockVideoBitrateAllocationObserver> bitrate_allocation_observer_;
   StrictMock<MockModuleRtpRtcp> rtp_rtcp_impl_;
diff --git a/modules/rtp_rtcp/source/rtp_rtcp_impl.cc b/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
index 9a0fc7c..f716718 100644
--- a/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
+++ b/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
@@ -74,6 +74,7 @@
                      configuration.rtcp_packet_type_counter_observer,
                      configuration.bandwidth_callback,
                      configuration.intra_frame_callback,
+                     configuration.rtcp_loss_notification_observer,
                      configuration.transport_feedback_callback,
                      configuration.bitrate_allocation_observer,
                      configuration.rtcp_report_interval_ms > 0
diff --git a/test/fuzzers/rtcp_receiver_fuzzer.cc b/test/fuzzers/rtcp_receiver_fuzzer.cc
index f729e55..f686121 100644
--- a/test/fuzzers/rtcp_receiver_fuzzer.cc
+++ b/test/fuzzers/rtcp_receiver_fuzzer.cc
@@ -40,7 +40,7 @@
   SimulatedClock clock(1234);
 
   RTCPReceiver receiver(&clock, false, nullptr, nullptr, nullptr, nullptr,
-                        nullptr, kRtcpIntervalMs, &rtp_rtcp_module);
+                        nullptr, nullptr, kRtcpIntervalMs, &rtp_rtcp_module);
 
   receiver.IncomingPacket(data, size);
 }
diff --git a/video/encoder_rtcp_feedback.cc b/video/encoder_rtcp_feedback.cc
index 2c54701..5a0920f 100644
--- a/video/encoder_rtcp_feedback.cc
+++ b/video/encoder_rtcp_feedback.cc
@@ -68,4 +68,12 @@
   video_stream_encoder_->SendKeyFrame();
 }
 
+void EncoderRtcpFeedback::OnReceivedLossNotification(
+    uint32_t ssrc,
+    uint16_t seq_num_of_last_decodable,
+    uint16_t seq_num_of_last_received,
+    bool decodability_flag) {
+  // TODO(eladalon): Handle.
+}
+
 }  // namespace webrtc
diff --git a/video/encoder_rtcp_feedback.h b/video/encoder_rtcp_feedback.h
index 1a58a67..4fa2335 100644
--- a/video/encoder_rtcp_feedback.h
+++ b/video/encoder_rtcp_feedback.h
@@ -27,16 +27,25 @@
 // TODO(bugs.webrtc.org/9719): Should be eliminated when RtpMediaTransport is
 // implemented.
 class EncoderRtcpFeedback : public RtcpIntraFrameObserver,
+                            public RtcpLossNotificationObserver,
                             public MediaTransportKeyFrameRequestCallback {
  public:
   EncoderRtcpFeedback(Clock* clock,
                       const std::vector<uint32_t>& ssrcs,
                       VideoStreamEncoderInterface* encoder);
+  ~EncoderRtcpFeedback() override = default;
+
   void OnReceivedIntraFrameRequest(uint32_t ssrc) override;
 
   // Implements MediaTransportKeyFrameRequestCallback
   void OnKeyFrameRequested(uint64_t channel_id) override;
 
+  // Implements RtcpLossNotificationObserver.
+  void OnReceivedLossNotification(uint32_t ssrc,
+                                  uint16_t seq_num_of_last_decodable,
+                                  uint16_t seq_num_of_last_received,
+                                  bool decodability_flag) override;
+
  private:
   bool HasSsrc(uint32_t ssrc);
 
diff --git a/video/video_send_stream_impl.cc b/video/video_send_stream_impl.cc
index 1acf0b3..f2a7756 100644
--- a/video/video_send_stream_impl.cc
+++ b/video/video_send_stream_impl.cc
@@ -149,6 +149,7 @@
   RtpSenderObservers observers;
   observers.rtcp_rtt_stats = call_stats;
   observers.intra_frame_callback = encoder_feedback;
+  observers.rtcp_loss_notification_observer = encoder_feedback;
   observers.rtcp_stats = stats_proxy;
   observers.rtp_stats = stats_proxy;
   observers.bitrate_observer = stats_proxy;