diff --git a/globals.ts b/globals.ts
index f25cc710b1..d38fbf47d2 100644
--- a/globals.ts
+++ b/globals.ts
@@ -1,4 +1,4 @@
-import { setTimeout } from "./timers";
+import * as timer from "./timers";
 
 // If you use the eval function indirectly, by invoking it via a reference
 // other than eval, as of ECMAScript 5 it works in the global scope rather than
@@ -14,7 +14,10 @@ export const _global = globalEval("this");
 _global["window"] = _global; // Create a window object.
 import "./url";
 
-_global["setTimeout"] = setTimeout;
+_global["setTimeout"] = timer.setTimeout;
+_global["setInterval"] = timer.setInterval;
+_global["clearTimeout"] = timer.clearTimer;
+_global["clearInterval"] = timer.clearTimer;
 
 const print = V8Worker2.print;
 
diff --git a/msg.proto b/msg.proto
index 081b2df8cb..68ff52255d 100644
--- a/msg.proto
+++ b/msg.proto
@@ -16,6 +16,7 @@ message Msg {
     ExitMsg exit = 14;
     TimerStartMsg timer_start = 15;
     TimerReadyMsg timer_ready = 16;
+    TimerClearMsg timer_clear = 17;
   }
 }
 
@@ -60,3 +61,5 @@ message TimerReadyMsg {
   optional int32 id = 1;
   optional bool done = 2;
 }
+
+message TimerClearMsg { optional int32 id = 1; }
diff --git a/testdata/004_set_timeout.ts b/testdata/004_set_timeout.ts
index fe55e31ba0..cc55bf76f7 100644
--- a/testdata/004_set_timeout.ts
+++ b/testdata/004_set_timeout.ts
@@ -3,3 +3,9 @@ setTimeout(function() {
 }, 10);
 
 console.log("Hello");
+
+const id = setTimeout(function() {
+  console.log("Not printed");
+}, 10000);
+
+clearTimeout(id);
diff --git a/testdata/010_set_interval.ts b/testdata/010_set_interval.ts
new file mode 100644
index 0000000000..e013d00bc6
--- /dev/null
+++ b/testdata/010_set_interval.ts
@@ -0,0 +1,7 @@
+const id = setInterval(function() {
+  console.log("test")
+}, 200);
+
+setTimeout(function() {
+  clearInterval(id)
+}, 500)
diff --git a/testdata/010_set_interval.ts.out b/testdata/010_set_interval.ts.out
new file mode 100644
index 0000000000..dec2cbe1fa
--- /dev/null
+++ b/testdata/010_set_interval.ts.out
@@ -0,0 +1,2 @@
+test
+test
diff --git a/timers.go b/timers.go
index f9fe28608e..6a395adaca 100644
--- a/timers.go
+++ b/timers.go
@@ -5,6 +5,16 @@ import (
 	"time"
 )
 
+type Timer struct {
+	Id       int32
+	Done     bool
+	Cleared  bool
+	Interval bool
+	Duration int32 // In milliseconds
+}
+
+var timers = make(map[int32]*Timer)
+
 func InitTimers() {
 	Sub("timers", func(buf []byte) []byte {
 		msg := &Msg{}
@@ -12,28 +22,62 @@ func InitTimers() {
 		switch msg.Payload.(type) {
 		case *Msg_TimerStart:
 			payload := msg.GetTimerStart()
-			return HandleTimerStart(*payload.Id, *payload.Interval,
-				*payload.Duration)
+			timers[*payload.Id] = &Timer{
+				Id:       *payload.Id,
+				Done:     false,
+				Interval: *payload.Interval,
+				Duration: *payload.Duration,
+				Cleared:  false,
+			}
+			timers[*payload.Id].StartTimer()
+			return nil
+		case *Msg_TimerClear:
+			payload := msg.GetTimerClear()
+			// TODO maybe need mutex here.
+			timer := timers[*payload.Id]
+			timer.Clear()
+			return nil
 		default:
 			panic("[timers] Unexpected message " + string(buf))
 		}
 	})
 }
 
-func HandleTimerStart(id int32, interval bool, duration int32) []byte {
+func (t *Timer) Clear() {
+	if !t.Cleared {
+		wg.Done()
+		t.Cleared = true
+		delete(timers, t.Id)
+	}
+	t.Done = true
+}
+
+func (t *Timer) StartTimer() {
 	wg.Add(1)
 	go func() {
-		defer wg.Done()
-		time.Sleep(time.Duration(duration) * time.Millisecond)
-		payload, err := proto.Marshal(&Msg{
-			Payload: &Msg_TimerReady{
-				TimerReady: &TimerReadyMsg{
-					Id: &id,
+		defer t.Clear()
+		for {
+			time.Sleep(time.Duration(t.Duration) * time.Millisecond)
+			if !t.Interval {
+				t.Done = true
+			}
+			pubMsg(&Msg{
+				Payload: &Msg_TimerReady{
+					TimerReady: &TimerReadyMsg{
+						Id:   &t.Id,
+						Done: &t.Done,
+					},
 				},
-			},
-		})
-		check(err)
-		Pub("timers", payload)
+			})
+			if t.Done {
+				return
+			}
+		}
 	}()
-	return nil
+}
+
+func pubMsg(msg *Msg) {
+	payload, err := proto.Marshal(msg)
+	check(err)
+	Pub("timers", payload)
 }
diff --git a/timers.ts b/timers.ts
index f5f039f1cd..5407c63b00 100644
--- a/timers.ts
+++ b/timers.ts
@@ -4,12 +4,14 @@ import * as dispatch from "./dispatch";
 let nextTimerId = 1;
 
 // tslint:disable-next-line:no-any
-type TimerCallback = (...args: any[]) => void;
+export type TimerCallback = (...args: any[]) => void;
 
 interface Timer {
   id: number;
   cb: TimerCallback;
   interval: boolean;
+  // tslint:disable-next-line:no-any
+  args: any[];
   duration: number; // milliseconds
 }
 
@@ -23,17 +25,26 @@ function onMessage(payload: Uint8Array) {
   const msg = pb.Msg.decode(payload);
   const { id, done } = msg.timerReady;
   const timer = timers.get(id);
-  timer.cb();
+  if (!timer) {
+    return;
+  }
+  timer.cb(...timer.args);
   if (done) {
     timers.delete(id);
   }
 }
 
-export function setTimeout(cb: TimerCallback, duration: number): number {
+export function setTimeout(
+  cb: TimerCallback,
+  duration: number,
+  // tslint:disable-next-line:no-any
+  ...args: any[]
+): number {
   const timer = {
     id: nextTimerId++,
     interval: false,
     duration,
+    args,
     cb
   };
   timers.set(timer.id, timer);
@@ -46,3 +57,34 @@ export function setTimeout(cb: TimerCallback, duration: number): number {
   });
   return timer.id;
 }
+
+// TODO DRY with setTimeout
+export function setInterval(
+  cb: TimerCallback,
+  repeat: number,
+  // tslint:disable-next-line:no-any
+  ...args: any[]
+): number {
+  const timer = {
+    id: nextTimerId++,
+    interval: true,
+    duration: repeat,
+    args,
+    cb
+  };
+  timers.set(timer.id, timer);
+  dispatch.sendMsg("timers", {
+    timerStart: {
+      id: timer.id,
+      interval: true,
+      duration: repeat
+    }
+  });
+  return timer.id;
+}
+
+export function clearTimer(id: number) {
+  dispatch.sendMsg("timers", {
+    timerClear: { id }
+  });
+}