diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index 46e458e95b..3a04b6f703 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -50,6 +50,7 @@ from synapse.rest.client.v2_alpha import (
     room_keys,
     room_upgrade_rest_servlet,
     sendtodevice,
+    shared_rooms,
     sync,
     tags,
     thirdparty,
@@ -113,6 +114,7 @@ class ClientRestResource(JsonResource):
         devices.register_servlets(hs, client_resource)
         thirdparty.register_servlets(hs, client_resource)
         sendtodevice.register_servlets(hs, client_resource)
+        shared_rooms.register_servlets(hs, client_resource)
         user_directory.register_servlets(hs, client_resource)
         groups.register_servlets(hs, client_resource)
         room_upgrade_rest_servlet.register_servlets(hs, client_resource)
diff --git a/synapse/rest/client/v2_alpha/shared_rooms.py b/synapse/rest/client/v2_alpha/shared_rooms.py
new file mode 100644
index 0000000000..11e18debf1
--- /dev/null
+++ b/synapse/rest/client/v2_alpha/shared_rooms.py
@@ -0,0 +1,50 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Half-Shot
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+from synapse.http.servlet import RestServlet
+from ._base import client_patterns
+
+logger = logging.getLogger(__name__)
+
+
+class UserSharedRoomsServlet(RestServlet):
+    """
+    GET /user/{user_id}/shared_rooms/(?P<other_user_id>[^/]*) HTTP/1.1
+    """
+
+    PATTERNS = client_patterns(
+        "/user/(?P<user_id>[^/]*)/shared_rooms/(?P<other_user_id>[^/]*)",
+        releases=(),  #  This is an unstable feature
+    )
+
+    def __init__(self, hs):
+        super(UserSharedRoomsServlet, self).__init__()
+        self.auth = hs.get_auth()
+        self.store = hs.get_datastore()
+
+    async def on_GET(self, request, user_id, other_user_id):
+        requester = await self.auth.get_user_by_req(request)
+        if user_id != requester.user.to_string():
+            raise AuthError(403, "Cannot get shared rooms for other users.")
+
+        rooms = await self.store.get_rooms_in_common_for_users(user_id, other_user_id)
+
+        return 200, rooms
+
+
+def register_servlets(hs, http_server):
+    UserSharedRoomsServlet(hs).register(http_server)