diff --git a/rx/core/observable/zip.py b/rx/core/observable/zip.py
index 8b7564771..f0d0c1a14 100644
--- a/rx/core/observable/zip.py
+++ b/rx/core/observable/zip.py
@@ -34,6 +34,7 @@ def subscribe(observer: typing.Observer,
         n = len(sources)
         queues: List[List] = [[] for _ in range(n)]
         lock = RLock()
+        is_completed = [False] * n
 
         @synchronized(lock)
         def next(i):
@@ -46,6 +47,14 @@ def next(i):
                     return
 
                 observer.on_next(res)
+            elif all([x for j, x in enumerate(is_completed) if j != i]) \
+                and all([len(x) == 0 for j, x in enumerate(queues) if j != i]):
+                observer.on_completed()
+
+        def completed(i):
+            is_completed[i] = True
+            if all(is_completed) or all([len(q) == 0 for q in queues]):
+                observer.on_completed()
 
         subscriptions = [None] * n
 
@@ -58,7 +67,7 @@ def on_next(x):
                 queues[i].append(x)
                 next(i)
 
-            sad.disposable = source.subscribe_(on_next, observer.on_error, observer.on_completed, scheduler)
+            sad.disposable = source.subscribe_(on_next, observer.on_error, lambda: completed(i), scheduler)
             subscriptions[i] = sad
 
         for idx in range(n):
diff --git a/tests/test_observable/test_zip.py b/tests/test_observable/test_zip.py
index fe09b4616..a14a79831 100644
--- a/tests/test_observable/test_zip.py
+++ b/tests/test_observable/test_zip.py
@@ -95,7 +95,7 @@ def create():
                 ops.map(sum))
 
         results = scheduler.start(create)
-        assert results.messages == [on_completed(220)]
+        assert results.messages == []
 
     def test_zip_non_empty_never(self):
         scheduler = TestScheduler()
@@ -109,7 +109,7 @@ def create():
                 ops.map(sum))
 
         results = scheduler.start(create)
-        assert results.messages == [on_completed(220)]
+        assert results.messages == []
 
     def test_zip_non_empty_non_empty(self):
         scheduler = TestScheduler()
@@ -126,6 +126,36 @@ def create():
         results = scheduler.start(create)
         assert results.messages == [on_next(220, 2 + 3), on_completed(230)]
 
+    def test_zip_non_empty_non_empty_sequential(self):
+        scheduler = TestScheduler()
+        msgs1 = [on_next(210, 1), on_next(215, 2), on_completed(230)]
+        msgs2 = [on_next(240, 1), on_next(245, 3), on_completed(250)]
+        e1 = scheduler.create_cold_observable(msgs1)
+        e2 = scheduler.create_cold_observable(msgs2)
+
+        def create():
+            return e1.pipe(
+                ops.zip(e2),
+                ops.map(sum))
+
+        results = scheduler.start(create)
+        assert results.messages == [on_next(200+240, 1 + 1), on_next(200+245, 2 + 3), on_completed(200+250)]
+
+    def test_zip_non_empty_partial_sequential(self):
+        scheduler = TestScheduler()
+        msgs1 = [on_next(210, 1), on_next(215, 2), on_completed(230)]
+        msgs2 = [on_next(240, 1), on_completed(250)]
+        e1 = scheduler.create_cold_observable(msgs1)
+        e2 = scheduler.create_cold_observable(msgs2)
+
+        def create():
+            return e1.pipe(
+                ops.zip(e2),
+                ops.map(sum))
+
+        results = scheduler.start(create)
+        assert results.messages == [on_next(200+240, 1 + 1), on_completed(200+250)]
+
     def test_zip_empty_error(self):
         ex = 'ex'
         scheduler = TestScheduler()