diff --git a/moto/autoscaling/models.py b/moto/autoscaling/models.py
index a47eac779..2dbdc077d 100644
--- a/moto/autoscaling/models.py
+++ b/moto/autoscaling/models.py
@@ -441,12 +441,25 @@ class AutoScalingBackend(BaseBackend):
             self.elb_backend.deregister_instances(elb.name, elb_instace_ids - group_instance_ids)
 
     def create_or_update_tags(self, tags):
+
         for tag in tags:
-            group_name = tag["ResourceId"]
+            group_name = tag["resource_id"]
             group = self.autoscaling_groups[group_name]
-            updated_tags = group.tags.copy()
-            updated_tags.update(tag)
-            group.tags = updated_tags
+            old_tags = group.tags
+
+            new_tags = []
+            #if key was in old_tags, update old tag
+            for old_tag in old_tags:
+                if old_tag["key"] == tag["key"]:
+                    new_tags.append(tag)
+                else:
+                    new_tags.append(old_tag)
+
+            #if key was never in old_tag's add it (create tag)
+            if not any(new_tag['key'] == tag['key'] for new_tag in new_tags):
+                new_tags.append(tag)
+
+            group.tags = new_tags
 
 autoscaling_backends = {}
 for region, ec2_backend in ec2_backends.items():
diff --git a/moto/autoscaling/responses.py b/moto/autoscaling/responses.py
index b3ec57f27..1840e029c 100644
--- a/moto/autoscaling/responses.py
+++ b/moto/autoscaling/responses.py
@@ -106,9 +106,11 @@ class AutoScalingResponse(BaseResponse):
         return template.render()
 
     def create_or_update_tags(self):
-        tags = self._get_param('Tags')
+        tags = self._get_list_prefix('Tags.member')
+
         self.autoscaling_backend.create_or_update_tags(tags)
-        return None
+        template = self.response_template(UPDATE_AUTOSCALING_GROUP_TEMPLATE)
+        return template.render()
 
     def describe_auto_scaling_instances(self):
         instance_states = self.autoscaling_backend.describe_autoscaling_instances()
diff --git a/tests/test_autoscaling/test_autoscaling.py b/tests/test_autoscaling/test_autoscaling.py
index 2f442c163..ea11b77e1 100644
--- a/tests/test_autoscaling/test_autoscaling.py
+++ b/tests/test_autoscaling/test_autoscaling.py
@@ -169,6 +169,48 @@ def test_autoscaling_update():
     group.vpc_zone_identifier.should.equal('subnet-5678efgh')
 
 
+@mock_autoscaling
+def test_autoscaling_tags_update():
+    conn = boto.connect_autoscale()
+    config = LaunchConfiguration(
+        name='tester',
+        image_id='ami-abcd1234',
+        instance_type='t2.medium',
+    )
+    conn.create_launch_configuration(config)
+
+    group = AutoScalingGroup(
+        name='tester_group',
+        availability_zones=['us-east-1c', 'us-east-1b'],
+        desired_capacity=2,
+        max_size=2,
+        min_size=2,
+        launch_config=config,
+        vpc_zone_identifier='subnet-1234abcd',
+        tags=[Tag(
+            resource_id='tester_group',
+            key='test_key',
+            value='test_value',
+            propagate_at_launch=True
+        )],
+    )
+    conn.create_auto_scaling_group(group)
+
+    conn.create_or_update_tags(tags=[Tag(
+            resource_id='tester_group',
+            key='test_key',
+            value='new_test_value',
+            propagate_at_launch=True
+        ), Tag(
+            resource_id='tester_group',
+            key='test_key2',
+            value='test_value2',
+            propagate_at_launch=True
+        )])
+    group = conn.get_all_groups()[0]
+    group.tags.should.have.length_of(2)
+
+
 @mock_autoscaling
 def test_autoscaling_group_delete():
     conn = boto.connect_autoscale()
@@ -420,6 +462,7 @@ def test_describe_autoscaling_groups_boto3():
         response['ResponseMetadata']['HTTPStatusCode'].should.equal(200)
         response['AutoScalingGroups'][0]['AutoScalingGroupName'].should.equal('test_asg')
 
+
 @mock_autoscaling
 def test_update_autoscaling_group_boto3():
     client = boto3.client('autoscaling', region_name='us-east-1')
@@ -443,3 +486,41 @@ def test_update_autoscaling_group_boto3():
         AutoScalingGroupNames=["test_asg"]
     )
     response['AutoScalingGroups'][0]['MinSize'].should.equal(1)
+
+
+@mock_autoscaling
+def test_autoscaling_taqs_update_boto3():
+    client = boto3.client('autoscaling', region_name='us-east-1')
+    _ = client.create_launch_configuration(
+        LaunchConfigurationName='test_launch_configuration'
+    )
+    _ = client.create_auto_scaling_group(
+        AutoScalingGroupName='test_asg',
+        LaunchConfigurationName='test_launch_configuration',
+        MinSize=0,
+        MaxSize=20,
+        DesiredCapacity=5,
+        Tags=[{
+            "ResourceId": 'test_asg',
+            "Key": 'test_key',
+            "Value": 'test_value',
+            "PropagateAtLaunch": True
+        }]
+    )
+
+    client.create_or_update_tags(Tags=[{
+            "ResourceId": 'test_asg',
+            "Key": 'test_key',
+            "Value": 'updated_test_value',
+            "PropagateAtLaunch": True
+        }, {
+            "ResourceId": 'test_asg',
+            "Key": 'test_key2',
+            "Value": 'test_value2',
+            "PropagateAtLaunch": True
+        }])
+
+    response = client.describe_auto_scaling_groups(
+        AutoScalingGroupNames=["test_asg"]
+    )
+    response['AutoScalingGroups'][0]['Tags'].should.have.length_of(2)