diff --git a/lib/client.js b/lib/client.js
index be453083e..d2dfe9435 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -725,6 +725,28 @@ MatrixClient.prototype.resendEvent = function(event, room) {
     return _sendEvent(this, room, event);
 };
 
+/**
+ * Cancel a queued or unsent event.
+ *
+ * @param {MatrixEvent} event   Event to cancel
+ * @throws Error if the event is not in QUEUED or NOT_SENT state
+ */
+MatrixClient.prototype.cancelPendingEvent = function(event) {
+    if ([EventStatus.QUEUED, EventStatus.NOT_SENT].indexOf(event.status) < 0) {
+        throw new Error("cannot cancel an event with status " + event.status);
+    }
+
+    // first tell the scheduler to forget about it, if it's queued
+    if (this.scheduler) {
+        this.scheduler.removeEventFromQueue(event);
+    }
+
+    // then tell the room about the change of state, which will remove it
+    // from the room's list of pending events.
+    var room = this.getRoom(event.getRoomId());
+    _updatePendingEventStatus(room, event, EventStatus.CANCELLED);
+};
+
 /**
  * @param {string} roomId
  * @param {string} name
diff --git a/lib/models/event.js b/lib/models/event.js
index de5287dcd..d39a8daf2 100644
--- a/lib/models/event.js
+++ b/lib/models/event.js
@@ -36,6 +36,9 @@ module.exports.EventStatus = {
     /** The event has been sent to the server, but we have not yet received the
      * echo. */
     SENT: "sent",
+
+    /** The event was cancelled before it was successfully sent. */
+    CANCELLED: "cancelled",
 };
 
 /**
diff --git a/lib/models/room.js b/lib/models/room.js
index dc4a9ed74..0f5881ba8 100644
--- a/lib/models/room.js
+++ b/lib/models/room.js
@@ -729,13 +729,16 @@ ALLOWED_TRANSITIONS[EventStatus.SENDING] =
     [EventStatus.QUEUED, EventStatus.NOT_SENT, EventStatus.SENT];
 
 ALLOWED_TRANSITIONS[EventStatus.QUEUED] =
-    [EventStatus.SENDING];
+    [EventStatus.SENDING, EventStatus.CANCELLED];
 
 ALLOWED_TRANSITIONS[EventStatus.SENT] =
     [];
 
 ALLOWED_TRANSITIONS[EventStatus.NOT_SENT] =
-    [EventStatus.SENDING, EventStatus.QUEUED];
+    [EventStatus.SENDING, EventStatus.QUEUED, EventStatus.CANCELLED];
+
+ALLOWED_TRANSITIONS[EventStatus.CANCELLED] =
+    [];
 
 /**
  * Update the status / event id on a pending event, to reflect its transmission
@@ -797,6 +800,17 @@ Room.prototype.updatePendingEvent = function(event, newStatus, newEventId) {
             this._eventIdToTimeline[newEventId] = existingTimeline;
         }
     }
+    else if (newStatus == EventStatus.CANCELLED) {
+        // remove it from the pending event list, or the timeline.
+        if (this._pendingEventList) {
+            utils.removeElement(
+                this._pendingEventList,
+                function(ev) { return ev.getId() == oldEventId; },
+                false
+            );
+        }
+        this.removeEvent(oldEventId);
+    }
 
     this.emit("Room.localEchoUpdated", event, this, event.getId(), oldStatus);
 };
@@ -1479,9 +1493,10 @@ module.exports = Room;
  * arrived, the event is updated with a new event id and the status is set to
  * 'SENT'. The server-generated fields are of course not updated yet.
  *
- * <p>Finally, the /send might fail. In this case, the event's status is set to
+ * <p>If the /send fails, In this case, the event's status is set to
  * 'NOT_SENT'. If it is later resent, the process starts again, setting the
- * status to 'SENDING'.
+ * status to 'SENDING'. Alternatively, the message may be cancelled, which
+ * removes the event from the room, and sets the status to 'CANCELLED'.
  *
  * <p>This event is raised to reflect each of the transitions above.
  *
diff --git a/spec/integ/matrix-client-retrying.spec.js b/spec/integ/matrix-client-retrying.spec.js
index 37544c1e3..4eabbdcfb 100644
--- a/spec/integ/matrix-client-retrying.spec.js
+++ b/spec/integ/matrix-client-retrying.spec.js
@@ -2,22 +2,30 @@
 var sdk = require("../..");
 var HttpBackend = require("../mock-request");
 var utils = require("../test-utils");
+var EventStatus = sdk.EventStatus;
 
 describe("MatrixClient retrying", function() {
     var baseUrl = "http://localhost.or.something";
     var client, httpBackend;
+    var scheduler;
     var userId = "@alice:localhost";
     var accessToken = "aseukfgwef";
+    var roomId = "!room:here";
+    var room;
 
     beforeEach(function() {
         utils.beforeEach(this);
         httpBackend = new HttpBackend();
         sdk.request(httpBackend.requestFn);
+        scheduler = new sdk.MatrixScheduler();
         client = sdk.createClient({
             baseUrl: baseUrl,
             userId: userId,
-            accessToken: accessToken
+            accessToken: accessToken,
+            scheduler: scheduler,
         });
+        room = new sdk.Room(roomId);
+        client.store.storeRoom(room);
     });
 
     afterEach(function() {
@@ -40,6 +48,49 @@ describe("MatrixClient retrying", function() {
 
     });
 
+    it("should mark events as EventStatus.CANCELLED when cancelled", function(done) {
+
+        // send a couple of events; the second will be queued
+        var ev1, ev2;
+        client.sendMessage(roomId, "m1").then(function(ev) {
+            expect(ev).toEqual(ev1);
+        });
+        client.sendMessage(roomId, "m2").then(function(ev) {
+            expect(ev).toEqual(ev2);
+        });
+
+        // both events should be in the timeline at this point
+        var tl = room.getLiveTimeline().getEvents();
+        expect(tl.length).toEqual(2);
+        ev1 = tl[0];
+        ev2 = tl[1];
+
+        expect(ev1.status).toEqual(EventStatus.SENDING);
+        expect(ev2.status).toEqual(EventStatus.QUEUED);
+
+        // now we can cancel the second and check everything looks sane
+        client.cancelPendingEvent(ev2);
+        expect(ev2.status).toEqual(EventStatus.CANCELLED);
+        expect(tl.length).toEqual(1);
+
+        // shouldn't be able to cancel the first message yet
+        expect(function() { client.cancelPendingEvent(ev1); })
+            .toThrow();
+
+        // fail the first send
+        httpBackend.when("PUT", "/send/m.room.message/")
+            .respond(400);
+        httpBackend.flush().then(function() {
+            expect(ev1.status).toEqual(EventStatus.NOT_SENT);
+            expect(tl.length).toEqual(1);
+
+            // cancel the first message
+            client.cancelPendingEvent(ev1);
+            expect(ev1.status).toEqual(EventStatus.CANCELLED);
+            expect(tl.length).toEqual(0);
+        }).catch(utils.failTest).done(done);
+    });
+
     describe("resending", function() {
         xit("should be able to resend a NOT_SENT event", function() {
 
diff --git a/spec/unit/room.spec.js b/spec/unit/room.spec.js
index e7a5848fa..fb0fd6c19 100644
--- a/spec/unit/room.spec.js
+++ b/spec/unit/room.spec.js
@@ -1225,4 +1225,76 @@ describe("Room", function() {
             );
         });
     });
+
+    describe("updatePendingEvent", function() {
+        it("should remove cancelled events from the pending list", function() {
+            var room = new Room(roomId, {
+                pendingEventOrdering: "detached"
+            });
+            var eventA = utils.mkMessage({
+                room: roomId, user: userA, event: true
+            });
+            eventA.status = EventStatus.SENDING;
+            var eventId = eventA.getId();
+
+            room.addPendingEvent(eventA, "TXN1");
+            expect(room.getPendingEvents()).toEqual(
+                [eventA]
+            );
+
+            // the event has to have been failed or queued before it can be
+            // cancelled
+            room.updatePendingEvent(eventA, EventStatus.NOT_SENT);
+
+            var callCount = 0;
+            room.on("Room.localEchoUpdated",
+                function(event, emitRoom, oldEventId, oldStatus) {
+                    expect(event).toEqual(eventA);
+                    expect(event.status).toEqual(EventStatus.CANCELLED);
+                    expect(emitRoom).toEqual(room);
+                    expect(oldEventId).toEqual(eventId);
+                    expect(oldStatus).toEqual(EventStatus.NOT_SENT);
+                    callCount++;
+                });
+
+            room.updatePendingEvent(eventA, EventStatus.CANCELLED);
+            expect(room.getPendingEvents()).toEqual([]);
+            expect(callCount).toEqual(1);
+        });
+
+
+        it("should remove cancelled events from the timeline", function() {
+            var room = new Room(roomId);
+            var eventA = utils.mkMessage({
+                room: roomId, user: userA, event: true
+            });
+            eventA.status = EventStatus.SENDING;
+            var eventId = eventA.getId();
+
+            room.addPendingEvent(eventA, "TXN1");
+            expect(room.getLiveTimeline().getEvents()).toEqual(
+                [eventA]
+            );
+
+            // the event has to have been failed or queued before it can be
+            // cancelled
+            room.updatePendingEvent(eventA, EventStatus.NOT_SENT);
+
+            var callCount = 0;
+            room.on("Room.localEchoUpdated",
+                function(event, emitRoom, oldEventId, oldStatus) {
+                    expect(event).toEqual(eventA);
+                    expect(event.status).toEqual(EventStatus.CANCELLED);
+                    expect(emitRoom).toEqual(room);
+                    expect(oldEventId).toEqual(eventId);
+                    expect(oldStatus).toEqual(EventStatus.NOT_SENT);
+                    callCount++;
+                });
+
+            room.updatePendingEvent(eventA, EventStatus.CANCELLED);
+            expect(room.getLiveTimeline().getEvents()).toEqual([]);
+            expect(callCount).toEqual(1);
+        });
+
+    });
 });