diff --git a/neutron/db/db_base_plugin_v2.py b/neutron/db/db_base_plugin_v2.py
index 3f8adc3850..b6288ddfab 100644
--- a/neutron/db/db_base_plugin_v2.py
+++ b/neutron/db/db_base_plugin_v2.py
@@ -1279,9 +1279,13 @@ class NeutronDbPluginV2(neutron_plugin_base_v2.NeutronPluginBaseV2,
                          filter_by(network_id=subnet['network_id']).
                          with_lockmode('update'))
 
-            # remove network owned ports
+            # Remove network owned ports, and delete IP allocations
+            # for IPv6 addresses which were automatically generated
+            # via SLAAC
+            is_ipv6_slaac_subnet = ipv6_utils.is_slaac_subnet(subnet)
             for a in allocated:
-                if a.ports.device_owner in AUTO_DELETE_PORT_OWNERS:
+                if (is_ipv6_slaac_subnet or
+                    a.ports.device_owner in AUTO_DELETE_PORT_OWNERS):
                     NeutronDbPluginV2._delete_ip_allocation(
                         context, subnet.network_id, id, a.ip_address)
                 else:
diff --git a/neutron/plugins/ml2/plugin.py b/neutron/plugins/ml2/plugin.py
index 0f596a66c2..09c6e95239 100644
--- a/neutron/plugins/ml2/plugin.py
+++ b/neutron/plugins/ml2/plugin.py
@@ -31,6 +31,7 @@ from neutron.api.rpc.handlers import securitygroups_rpc
 from neutron.api.v2 import attributes
 from neutron.common import constants as const
 from neutron.common import exceptions as exc
+from neutron.common import ipv6_utils
 from neutron.common import rpc as n_rpc
 from neutron.common import topics
 from neutron.common import utils
@@ -729,7 +730,8 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                 LOG.debug(_("Ports to auto-deallocate: %s"), allocated)
                 only_auto_del = all(not a.port_id or
                                     a.ports.device_owner in db_base_plugin_v2.
-                                    AUTO_DELETE_PORT_OWNERS
+                                    AUTO_DELETE_PORT_OWNERS or
+                                    ipv6_utils.is_slaac_subnet(subnet)
                                     for a in allocated)
                 if not only_auto_del:
                     LOG.debug(_("Tenant-owned ports exist"))
diff --git a/neutron/tests/unit/test_db_plugin.py b/neutron/tests/unit/test_db_plugin.py
index 465183fcdd..b5051b38e2 100644
--- a/neutron/tests/unit/test_db_plugin.py
+++ b/neutron/tests/unit/test_db_plugin.py
@@ -2641,6 +2641,36 @@ class TestSubnetsV2(NeutronDbPluginV2TestCase):
                     self.assertEqual(res.status_int,
                                      webob.exc.HTTPNoContent.code)
 
+    def test_delete_subnet_ipv6_slaac_port_exists(self):
+        """Test IPv6 SLAAC subnet delete when a port is still using subnet."""
+        res = self._create_network(fmt=self.fmt, name='net',
+                                   admin_state_up=True)
+        network = self.deserialize(self.fmt, res)
+        # Create an IPv6 SLAAC subnet and a port using that subnet
+        subnet = self._make_subnet(self.fmt, network, gateway='fe80::1',
+                                   cidr='fe80::/64', ip_version=6,
+                                   ipv6_ra_mode=constants.IPV6_SLAAC,
+                                   ipv6_address_mode=constants.IPV6_SLAAC)
+        res = self._create_port(self.fmt, net_id=network['network']['id'])
+        port = self.deserialize(self.fmt, res)
+        self.assertEqual(1, len(port['port']['fixed_ips']))
+
+        # The port should have an address from the subnet
+        req = self.new_show_request('ports', port['port']['id'], self.fmt)
+        res = req.get_response(self.api)
+        sport = self.deserialize(self.fmt, req.get_response(self.api))
+        self.assertEqual(1, len(sport['port']['fixed_ips']))
+
+        # Delete the subnet
+        req = self.new_delete_request('subnets', subnet['subnet']['id'])
+        res = req.get_response(self.api)
+        self.assertEqual(webob.exc.HTTPNoContent.code, res.status_int)
+        # The port should no longer have an address from the deleted subnet
+        req = self.new_show_request('ports', port['port']['id'], self.fmt)
+        res = req.get_response(self.api)
+        sport = self.deserialize(self.fmt, req.get_response(self.api))
+        self.assertEqual(0, len(sport['port']['fixed_ips']))
+
     def test_delete_network(self):
         gateway_ip = '10.0.0.1'
         cidr = '10.0.0.0/24'