diff --git a/moto/ec2/models.py b/moto/ec2/models.py
index 543960da0..9c30cb119 100644
--- a/moto/ec2/models.py
+++ b/moto/ec2/models.py
@@ -2494,6 +2494,14 @@ class VpnGatewayBackend(object):
             raise InvalidVpnGatewayIdError(vpn_gateway_id)
         return deleted
 
+    def detach_vpn_gateway(self, vpn_gateway_id, vpc_id):
+        vpn_gateway = self.get_vpn_gateway(vpn_gateway_id)
+        self.get_vpc(vpc_id)
+        detached = vpn_gateway.attachments.pop(vpc_id, None)
+        if not detached:
+            raise InvalidVPCIdError(vpc_id)
+        return detached
+
 
 class EC2Backend(BaseBackend, InstanceBackend, TagBackend, AmiBackend,
                  RegionsAndZonesBackend, SecurityGroupBackend, EBSBackend,
diff --git a/moto/ec2/responses/virtual_private_gateways.py b/moto/ec2/responses/virtual_private_gateways.py
index 94533943e..50b5704ea 100644
--- a/moto/ec2/responses/virtual_private_gateways.py
+++ b/moto/ec2/responses/virtual_private_gateways.py
@@ -34,8 +34,14 @@ class VirtualPrivateGateways(BaseResponse):
         return template.render(vpn_gateways=vpn_gateways)
 
     def detach_vpn_gateway(self):
-        raise NotImplementedError('VirtualPrivateGateways(AmazonVPC).detach_vpn_gateway is not yet implemented')
-
+        vpn_gateway_id = self.querystring.get('VpnGatewayId')[0]
+        vpc_id = self.querystring.get('VpcId')[0]
+        attachment = self.ec2_backend.detach_vpn_gateway(
+            vpn_gateway_id,
+            vpc_id
+        )
+        template = Template(DETACH_VPN_GATEWAY_RESPONSE)
+        return template.render(attachment=attachment)
 
 CREATE_VPN_GATEWAY_RESPONSE = """
 <CreateVpnGatewayResponse xmlns="http://ec2.amazonaws.com/doc/2014-10-01/">
@@ -107,4 +113,11 @@ DELETE_VPN_GATEWAY_RESPONSE = """
    <requestId>7a62c49f-347e-4fc4-9331-6e8eEXAMPLE</requestId>
    <return>true</return>
 </DeleteVpnGatewayResponse>
+"""
+
+DETACH_VPN_GATEWAY_RESPONSE = """
+<DetachVpnGatewayResponse xmlns="http://ec2.amazonaws.com/doc/2014-10-01/">
+   <requestId>7a62c49f-347e-4fc4-9331-6e8eEXAMPLE</requestId>
+   <return>true</return>
+</DetachVpnGatewayResponse>
 """
\ No newline at end of file
diff --git a/tests/test_ec2/test_virtual_private_gateways.py b/tests/test_ec2/test_virtual_private_gateways.py
index 40a03038e..8050559f1 100644
--- a/tests/test_ec2/test_virtual_private_gateways.py
+++ b/tests/test_ec2/test_virtual_private_gateways.py
@@ -74,3 +74,31 @@ def test_vpn_gateway_tagging():
     vpn_gateway = conn.get_all_vpn_gateways()[0]
     vpn_gateway.tags.should.have.length_of(1)
     vpn_gateway.tags["a key"].should.equal("some value")
+
+
+@mock_ec2
+def test_detach_vpn_gateway():
+
+    conn = boto.connect_vpc('the_key', 'the_secret')
+    vpc = conn.create_vpc("10.0.0.0/16")
+    vpn_gateway = conn.create_vpn_gateway('ipsec.1', 'us-east-1a')
+
+    conn.attach_vpn_gateway(
+        vpn_gateway_id=vpn_gateway.id,
+        vpc_id=vpc.id
+    )
+
+    gateway = conn.get_all_vpn_gateways()[0]
+    attachments = gateway.attachments
+    attachments.should.have.length_of(1)
+    attachments[0].vpc_id.should.equal(vpc.id)
+    attachments[0].state.should.equal('attached')
+
+    conn.detach_vpn_gateway(
+        vpn_gateway_id=vpn_gateway.id,
+        vpc_id=vpc.id
+    )
+
+    gateway = conn.get_all_vpn_gateways()[0]
+    attachments = gateway.attachments
+    attachments.should.have.length_of(0)