diff --git a/docs/api/schemas/latest/patchwork.yaml b/docs/api/schemas/latest/patchwork.yaml
index cd33291..66eecdd 100644
--- a/docs/api/schemas/latest/patchwork.yaml
+++ b/docs/api/schemas/latest/patchwork.yaml
@@ -1032,6 +1032,176 @@ paths:
                 $ref: '#/components/schemas/Error'
       tags:
         - series
+  /api/relations/:
+    get:
+      description: List relations.
+      operationId: relations_list
+      parameters:
+        - $ref: '#/components/parameters/Page'
+        - $ref: '#/components/parameters/PageSize'
+        - $ref: '#/components/parameters/Order'
+      responses:
+        '200':
+          description: ''
+          headers:
+            Link:
+              $ref: '#/components/headers/Link'
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/Relation'
+      tags:
+        - relations
+    post:
+      description: Create a relation.
+      operationId: relations_create
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '201':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Invalid Request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - checks
+  /api/relations/{id}/:
+    get:
+      description: Show a relation.
+      operationId: relation_read
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
+    patch:
+      description: Update a relation (partial).
+      operationId: relations_partial_update
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Bad request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
+    put:
+      description: Update a relation.
+      operationId: relations_update
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Bad request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
   /api/users/:
     get:
       description: List users.
@@ -1307,6 +1477,18 @@ components:
         application/x-www-form-urlencoded:
           schema:
             $ref: '#/components/schemas/User'
+    Relation:
+      required: true
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
+        multipart/form-data:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
+        application/x-www-form-urlencoded:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
   schemas:
     Index:
       type: object
@@ -1351,6 +1533,11 @@ components:
           type: string
           format: uri
           readOnly: true
+        relations:
+          title: Relations URL
+          type: string
+          format: uri
+          readOnly: true
     Bundle:
       required:
         - name
@@ -1929,6 +2116,14 @@ components:
           title: Delegate
           type: integer
           nullable: true
+    RelationUpdate:
+      type: object
+      properties:
+        submissions:
+          title: Submission IDs
+          type: array
+          items:
+            type: integer
     Person:
       type: object
       properties:
@@ -2119,6 +2314,22 @@ components:
             $ref: '#/components/schemas/PatchEmbedded'
           readOnly: true
           uniqueItems: true
+    Relation:
+      type: object
+      properties:
+        id:
+          title: ID
+          type: integer
+        url:
+          title: URL
+          type: string
+          format: uri
+          readOnly: true
+        submissions:
+          type: array
+          items:
+            type: integer
+          uniqueItems: true
     User:
       type: object
       properties:
@@ -2530,6 +2741,13 @@ components:
           type: string
           format: uri
           readOnly: true
+    ErrorRelation:
+      type: object
+      properties:
+        submissions:
+          type: array
+          items:
+            type: string
     ErrorUserUpdate:
       type: object
       properties:
diff --git a/docs/api/schemas/patchwork.j2 b/docs/api/schemas/patchwork.j2
index 6116578..6050b7d 100644
--- a/docs/api/schemas/patchwork.j2
+++ b/docs/api/schemas/patchwork.j2
@@ -1037,6 +1037,178 @@ paths:
                 $ref: '#/components/schemas/Error'
       tags:
         - series
+{% if version >= (1, 2) %}
+  /api/{{ version_url }}relations/:
+    get:
+      description: List relations.
+      operationId: relations_list
+      parameters:
+        - $ref: '#/components/parameters/Page'
+        - $ref: '#/components/parameters/PageSize'
+        - $ref: '#/components/parameters/Order'
+      responses:
+        '200':
+          description: ''
+          headers:
+            Link:
+              $ref: '#/components/headers/Link'
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/Relation'
+      tags:
+        - relations
+    post:
+      description: Create a relation.
+      operationId: relations_create
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '201':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Invalid Request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - checks
+  /api/{{ version_url }}relations/{id}/:
+    get:
+      description: Show a relation.
+      operationId: relation_read
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
+    patch:
+      description: Update a relation (partial).
+      operationId: relations_partial_update
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Bad request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
+    put:
+      description: Update a relation.
+      operationId: relations_update
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Bad request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
+{% endif %}
   /api/{{ version_url }}users/:
     get:
       description: List users.
@@ -1314,6 +1486,20 @@ components:
         application/x-www-form-urlencoded:
           schema:
             $ref: '#/components/schemas/User'
+{% if version >= (1, 2) %}
+    Relation:
+      required: true
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
+        multipart/form-data:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
+        application/x-www-form-urlencoded:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
+{% endif %}
   schemas:
     Index:
       type: object
@@ -1358,6 +1544,13 @@ components:
           type: string
           format: uri
           readOnly: true
+{% if version >= (1, 2) %}
+        relations:
+          title: Relations URL
+          type: string
+          format: uri
+          readOnly: true
+{% endif %}
     Bundle:
       required:
         - name
@@ -1961,6 +2154,16 @@ components:
           title: Delegate
           type: integer
           nullable: true
+{% if version >= (1, 2) %}
+    RelationUpdate:
+      type: object
+      properties:
+        submissions:
+          title: Submission IDs
+          type: array
+          items:
+            type: integer
+{% endif %}
     Person:
       type: object
       properties:
@@ -2157,6 +2360,24 @@ components:
             $ref: '#/components/schemas/PatchEmbedded'
           readOnly: true
           uniqueItems: true
+{% if version >= (1, 2) %}
+    Relation:
+      type: object
+      properties:
+        id:
+          title: ID
+          type: integer
+        url:
+          title: URL
+          type: string
+          format: uri
+          readOnly: true
+        submissions:
+          type: array
+          items:
+            type: integer
+          uniqueItems: true
+{% endif %}
     User:
       type: object
       properties:
@@ -2582,6 +2803,15 @@ components:
           type: string
           format: uri
           readOnly: true
+{% if version >= (1, 2) %}
+    ErrorRelation:
+      type: object
+      properties:
+        submissions:
+          type: array
+          items:
+            type: string
+{% endif %}
     ErrorUserUpdate:
       type: object
       properties:
diff --git a/docs/api/schemas/v1.2/patchwork.yaml b/docs/api/schemas/v1.2/patchwork.yaml
index 30cadcc..116ee64 100644
--- a/docs/api/schemas/v1.2/patchwork.yaml
+++ b/docs/api/schemas/v1.2/patchwork.yaml
@@ -1032,6 +1032,176 @@ paths:
                 $ref: '#/components/schemas/Error'
       tags:
         - series
+  /api/1.2/relations/:
+    get:
+      description: List relations.
+      operationId: relations_list
+      parameters:
+        - $ref: '#/components/parameters/Page'
+        - $ref: '#/components/parameters/PageSize'
+        - $ref: '#/components/parameters/Order'
+      responses:
+        '200':
+          description: ''
+          headers:
+            Link:
+              $ref: '#/components/headers/Link'
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/Relation'
+      tags:
+        - relations
+    post:
+      description: Create a relation.
+      operationId: relations_create
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '201':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Invalid Request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - checks
+  /api/1.2/relations/{id}/:
+    get:
+      description: Show a relation.
+      operationId: relation_read
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
+    patch:
+      description: Update a relation (partial).
+      operationId: relations_partial_update
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Bad request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
+    put:
+      description: Update a relation.
+      operationId: relations_update
+      security:
+        - basicAuth: []
+        - apiKeyAuth: []
+      parameters:
+        - in: path
+          name: id
+          description: A unique integer value identifying this relation.
+          required: true
+          schema:
+            title: ID
+            type: integer
+      requestBody:
+        $ref: '#/components/requestBodies/Relation'
+      responses:
+        '200':
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Relation'
+        '400':
+          description: Bad request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorRelation'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+        '404':
+          description: Not found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+      tags:
+        - relations
   /api/1.2/users/:
     get:
       description: List users.
@@ -1307,6 +1477,18 @@ components:
         application/x-www-form-urlencoded:
           schema:
             $ref: '#/components/schemas/User'
+    Relation:
+      required: true
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
+        multipart/form-data:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
+        application/x-www-form-urlencoded:
+          schema:
+            $ref: '#/components/schemas/RelationUpdate'
   schemas:
     Index:
       type: object
@@ -1351,6 +1533,11 @@ components:
           type: string
           format: uri
           readOnly: true
+        relations:
+          title: Relations URL
+          type: string
+          format: uri
+          readOnly: true
     Bundle:
       required:
         - name
@@ -1929,6 +2116,14 @@ components:
           title: Delegate
           type: integer
           nullable: true
+    RelationUpdate:
+      type: object
+      properties:
+        submissions:
+          title: Submission IDs
+          type: array
+          items:
+            type: integer
     Person:
       type: object
       properties:
@@ -2119,6 +2314,22 @@ components:
             $ref: '#/components/schemas/PatchEmbedded'
           readOnly: true
           uniqueItems: true
+    Relation:
+      type: object
+      properties:
+        id:
+          title: ID
+          type: integer
+        url:
+          title: URL
+          type: string
+          format: uri
+          readOnly: true
+        submissions:
+          type: array
+          items:
+            type: integer
+          uniqueItems: true
     User:
       type: object
       properties:
@@ -2530,6 +2741,13 @@ components:
           type: string
           format: uri
           readOnly: true
+    ErrorRelation:
+      type: object
+      properties:
+        submissions:
+          type: array
+          items:
+            type: string
     ErrorUserUpdate:
       type: object
       properties:
diff --git a/patchwork/api/index.py b/patchwork/api/index.py
index 45485c9..cf18453 100644
--- a/patchwork/api/index.py
+++ b/patchwork/api/index.py
@@ -21,4 +21,5 @@ class IndexView(APIView):
             'series': reverse('api-series-list', request=request),
             'events': reverse('api-event-list', request=request),
             'bundles': reverse('api-bundle-list', request=request),
+            'relations': reverse('api-relation-list', request=request),
         })
diff --git a/patchwork/api/relation.py b/patchwork/api/relation.py
new file mode 100644
index 0000000..e7d002b
--- /dev/null
+++ b/patchwork/api/relation.py
@@ -0,0 +1,73 @@
+# Patchwork - automated patch tracking system
+# Copyright (C) 2019, Bayerische Motoren Werke Aktiengesellschaft (BMW AG)
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+from django.db.models import Count
+from rest_framework import permissions
+from rest_framework.generics import ListCreateAPIView
+from rest_framework.generics import RetrieveUpdateDestroyAPIView
+from rest_framework.serializers import ModelSerializer
+
+from patchwork.models import SubmissionRelation
+
+
+class MaintainerPermission(permissions.BasePermission):
+
+    def has_object_permission(self, request, view, submissions):
+        if request.method in permissions.SAFE_METHODS:
+            return True
+
+        user = request.user
+        if not user.is_authenticated:
+            return False
+
+        if isinstance(submissions, SubmissionRelation):
+            submissions = list(submissions.submissions.all())
+        maintaining = user.profile.maintainer_projects.all()
+        return all(s.project in maintaining for s in submissions)
+
+    def has_permission(self, request, view):
+        return request.method in permissions.SAFE_METHODS or \
+               (request.user.is_authenticated and
+                request.user.profile.maintainer_projects.count() > 0)
+
+
+class SubmissionRelationSerializer(ModelSerializer):
+    class Meta:
+        model = SubmissionRelation
+        fields = ('id', 'url', 'submissions',)
+        read_only_fields = ('url',)
+        extra_kwargs = {
+            'url': {'view_name': 'api-relation-detail'},
+        }
+
+
+class SubmissionRelationMixin:
+    serializer_class = SubmissionRelationSerializer
+    permission_classes = (MaintainerPermission,)
+
+    def get_queryset(self):
+        return SubmissionRelation.objects.all() \
+            .prefetch_related('submissions')
+
+
+class SubmissionRelationList(SubmissionRelationMixin, ListCreateAPIView):
+    ordering = 'id'
+    ordering_fields = ['id', 'submission_count']
+
+    def create(self, request, *args, **kwargs):
+        serializer = self.get_serializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+        submissions = serializer.validated_data['submissions']
+        self.check_object_permissions(request, submissions)
+        return super().create(request, *args, **kwargs)
+
+    def get_queryset(self):
+        return super().get_queryset() \
+            .annotate(submission_count=Count('submission'))
+
+
+class SubmissionRelationDetail(SubmissionRelationMixin,
+                               RetrieveUpdateDestroyAPIView):
+    pass
diff --git a/patchwork/tests/api/test_relation.py b/patchwork/tests/api/test_relation.py
new file mode 100644
index 0000000..296926d
--- /dev/null
+++ b/patchwork/tests/api/test_relation.py
@@ -0,0 +1,194 @@
+# Patchwork - automated patch tracking system
+# Copyright (C) 2019, Bayerische Motoren Werke Aktiengesellschaft (BMW AG)
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import unittest
+from enum import Enum
+from enum import auto
+
+import six
+from django.conf import settings
+from django.urls import reverse
+
+from patchwork.models import SubmissionRelation
+from patchwork.tests.api import utils
+from patchwork.tests.utils import create_maintainer
+from patchwork.tests.utils import create_patches
+from patchwork.tests.utils import create_project
+from patchwork.tests.utils import create_relation
+from patchwork.tests.utils import create_user
+
+if settings.ENABLE_REST_API:
+    from rest_framework import status
+
+
+class UserType(Enum):
+    ANONYMOUS = auto()
+    NON_MAINTAINER = auto()
+    MAINTAINER = auto()
+
+@unittest.skipUnless(settings.ENABLE_REST_API, 'requires ENABLE_REST_API')
+class TestRelationAPI(utils.APITestCase):
+    fixtures = ['default_tags']
+
+    @staticmethod
+    def api_url(item=None):
+        kwargs = {}
+        if item is None:
+            return reverse('api-relation-list', kwargs=kwargs)
+        kwargs['pk'] = item
+        return reverse('api-relation-detail', kwargs=kwargs)
+
+    def request_restricted(self, method, user_type: UserType):
+        # setup
+
+        project = create_project()
+
+        if user_type == UserType.ANONYMOUS:
+            expected_status = status.HTTP_403_FORBIDDEN
+        elif user_type == UserType.NON_MAINTAINER:
+            expected_status = status.HTTP_403_FORBIDDEN
+            self.client.force_authenticate(user=create_user())
+        elif user_type == UserType.MAINTAINER:
+            if method == 'post':
+                expected_status = status.HTTP_201_CREATED
+            elif method == 'delete':
+                expected_status = status.HTTP_204_NO_CONTENT
+            else:
+                expected_status = status.HTTP_200_OK
+            user = create_maintainer(project)
+            self.client.force_authenticate(user=user)
+        else:
+            raise ValueError
+
+        resource_id = None
+        send = None
+
+        if method == 'delete':
+            resource_id = create_relation(project=project).id
+        elif method == 'post':
+            patch_ids = [p.id for p in create_patches(2, project=project)]
+            send = {'submissions': patch_ids}
+        elif method == 'patch':
+            resource_id = create_relation(project=project).id
+            patch_ids = [p.id for p in create_patches(2, project=project)]
+            send = {'submissions': patch_ids}
+        else:
+            raise ValueError
+
+        # request
+
+        resp = getattr(self.client, method)(self.api_url(resource_id), send)
+
+        # check
+
+        self.assertEqual(expected_status, resp.status_code)
+
+        if resp.status_code not in range(200, 202):
+            return
+
+        if resource_id:
+            self.assertEqual(resource_id, resp.data['id'])
+
+        send_ids = send['submissions']
+        resp_ids = resp.data['submissions']
+        six.assertCountEqual(self, resp_ids, send_ids)
+
+    def assertSerialized(self, obj: SubmissionRelation, resp: dict):
+        self.assertEqual(obj.id, resp['id'])
+        obj = [s.id for s in obj.submissions.all()]
+        six.assertCountEqual(self, obj, resp['submissions'])
+
+    def test_list_empty(self):
+        """List relation when none are present."""
+        resp = self.client.get(self.api_url())
+        self.assertEqual(status.HTTP_200_OK, resp.status_code)
+        self.assertEqual(0, len(resp.data))
+
+    @utils.store_samples('relation-list')
+    def test_list(self):
+        """List relations."""
+        relation = create_relation()
+
+        resp = self.client.get(self.api_url())
+        self.assertEqual(status.HTTP_200_OK, resp.status_code)
+        self.assertEqual(1, len(resp.data))
+        self.assertSerialized(relation, resp.data[0])
+
+    def test_detail(self):
+        """Show relation."""
+        relation = create_relation()
+
+        resp = self.client.get(self.api_url(relation.id))
+        self.assertEqual(status.HTTP_200_OK, resp.status_code)
+        self.assertSerialized(relation, resp.data)
+
+    @utils.store_samples('relation-update-error-forbidden')
+    def test_update_anonymous(self):
+        """Update relation as anonymous user.
+
+        Ensure updates can be performed by maintainers.
+        """
+        self.request_restricted('patch', UserType.ANONYMOUS)
+
+    def test_update_non_maintainer(self):
+        """Update relation as non-maintainer.
+
+        Ensure updates can be performed by maintainers.
+        """
+        self.request_restricted('patch', UserType.NON_MAINTAINER)
+
+    @utils.store_samples('relation-update')
+    def test_update_maintainer(self):
+        """Update relation as maintainer.
+
+        Ensure updates can be performed by maintainers.
+        """
+        self.request_restricted('patch', UserType.MAINTAINER)
+
+    @utils.store_samples('relation-delete-error-forbidden')
+    def test_delete_anonymous(self):
+        """Delete relation as anonymous user.
+
+        Ensure deletes can be performed by maintainers.
+        """
+        self.request_restricted('delete', UserType.ANONYMOUS)
+
+    def test_delete_non_maintainer(self):
+        """Delete relation as non-maintainer.
+
+        Ensure deletes can be performed by maintainers.
+        """
+        self.request_restricted('delete', UserType.NON_MAINTAINER)
+
+    @utils.store_samples('relation-update')
+    def test_delete_maintainer(self):
+        """Delete relation as maintainer.
+
+        Ensure deletes can be performed by maintainers.
+        """
+        self.request_restricted('delete', UserType.MAINTAINER)
+
+    @utils.store_samples('relation-create-error-forbidden')
+    def test_create_anonymous(self):
+        """Create relation as anonymous user.
+
+        Ensure creates can be performed by maintainers.
+        """
+        self.request_restricted('post', UserType.ANONYMOUS)
+
+    def test_create_non_maintainer(self):
+        """Create relation as non-maintainer.
+
+        Ensure creates can be performed by maintainers.
+        """
+        self.request_restricted('post', UserType.NON_MAINTAINER)
+
+    @utils.store_samples('relation-create')
+    def test_create_maintainer(self):
+        """Create relation as maintainer.
+
+        Ensure creates can be performed by maintainers.
+        """
+        self.request_restricted('post', UserType.MAINTAINER)
diff --git a/patchwork/tests/utils.py b/patchwork/tests/utils.py
index 577183d..47149de 100644
--- a/patchwork/tests/utils.py
+++ b/patchwork/tests/utils.py
@@ -16,6 +16,7 @@ from patchwork.models import Check
 from patchwork.models import Comment
 from patchwork.models import CoverLetter
 from patchwork.models import Patch
+from patchwork.models import SubmissionRelation
 from patchwork.models import Person
 from patchwork.models import Project
 from patchwork.models import Series
@@ -347,3 +348,13 @@ def create_covers(count=1, **kwargs):
         kwargs (dict): Overrides for various cover letter fields
     """
     return _create_submissions(create_cover, count, **kwargs)
+
+
+def create_relation(count_patches=2, **kwargs):
+    relation = SubmissionRelation.objects.create()
+    values = {
+        'related': relation
+    }
+    values.update(kwargs)
+    create_patches(count_patches, **values)
+    return relation
diff --git a/patchwork/urls.py b/patchwork/urls.py
index dcdcfb4..92095f6 100644
--- a/patchwork/urls.py
+++ b/patchwork/urls.py
@@ -187,6 +187,7 @@ if settings.ENABLE_REST_API:
     from patchwork.api import patch as api_patch_views  # noqa
     from patchwork.api import person as api_person_views  # noqa
     from patchwork.api import project as api_project_views  # noqa
+    from patchwork.api import relation as api_relation_views  # noqa
     from patchwork.api import series as api_series_views  # noqa
     from patchwork.api import user as api_user_views  # noqa
 
@@ -256,9 +257,19 @@ if settings.ENABLE_REST_API:
             name='api-cover-comment-list'),
     ]
 
+    api_1_2_patterns = [
+        url(r'^relations/$',
+            api_relation_views.SubmissionRelationList.as_view(),
+            name='api-relation-list'),
+        url(r'^relations/(?P<pk>[^/]+)/$',
+            api_relation_views.SubmissionRelationDetail.as_view(),
+            name='api-relation-detail'),
+    ]
+
     urlpatterns += [
         url(r'^api/(?:(?P<version>(1.0|1.1|1.2))/)?', include(api_patterns)),
         url(r'^api/(?:(?P<version>(1.1|1.2))/)?', include(api_1_1_patterns)),
+        url(r'^api/(?:(?P<version>1.2)/)?', include(api_1_2_patterns)),
 
         # token change
         url(r'^user/generate-token/$', user_views.generate_token,
diff --git a/releasenotes/notes/add-submission-relations-c96bb6c567b416d8.yaml b/releasenotes/notes/add-submission-relations-c96bb6c567b416d8.yaml
new file mode 100644
index 0000000..cb87799
--- /dev/null
+++ b/releasenotes/notes/add-submission-relations-c96bb6c567b416d8.yaml
@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Submissions (cover letters or patches) can now be related to other ones
+    (e.g. revisions). Relations can be set via the REST API by maintainers
+    (currently only for submissions of projects they maintain)
+api:
+  - |
+    Relations are available via ``/relations/`` and
+    ``/relations/{relationID}/`` endpoints.
