diff --git a/client/src/app/core/repositories/users/user-repository.service.ts b/client/src/app/core/repositories/users/user-repository.service.ts
index 0bb86f2ad..7d1a3cab8 100644
--- a/client/src/app/core/repositories/users/user-repository.service.ts
+++ b/client/src/app/core/repositories/users/user-repository.service.ts
@@ -263,6 +263,21 @@ export class UserRepositoryService extends BaseRepository<ViewUser, User, UserTi
         });
     }
 
+    /**
+     * Alters groups of all given users. Either adds or removes the given groups.
+     *
+     * @param users Affected users
+     * @param action add or remove the groups
+     * @param groupIds All group ids to add or remove
+     */
+    public async bulkAlterGroups(users: ViewUser[], action: 'add' | 'remove', groupIds: number[]): Promise<void> {
+        await this.httpService.post('/rest/users/user/bulk_alter_groups/', {
+            user_ids: users.map(user => user.id),
+            action: action,
+            group_ids: groupIds
+        });
+    }
+
     /**
      * Sends invitation emails to all given users. Returns a prepared string to show the user.
      * This string should always be shown, becuase even in success cases, some users may not get
diff --git a/client/src/app/site/users/components/user-detail/user-detail.component.html b/client/src/app/site/users/components/user-detail/user-detail.component.html
index 454d04f4e..083d5f368 100644
--- a/client/src/app/site/users/components/user-detail/user-detail.component.html
+++ b/client/src/app/site/users/components/user-detail/user-detail.component.html
@@ -290,8 +290,7 @@
     <div *ngIf="user.groups && user.groups.length > 0">
         <h4 translate>Groups</h4>
         <span *ngFor="let group of user.groups; let last = last">
-            {{ group.getTitle() | translate }}
-            <span *ngIf="!last">,&nbsp;</span>
+            {{ group.getTitle() | translate }}<span *ngIf="!last">,&nbsp;</span>
         </span>
     </div>
 
diff --git a/client/src/app/site/users/components/user-list/user-list.component.ts b/client/src/app/site/users/components/user-list/user-list.component.ts
index a8231a56b..8d661db4a 100644
--- a/client/src/app/site/users/components/user-list/user-list.component.ts
+++ b/client/src/app/site/users/components/user-list/user-list.component.ts
@@ -302,18 +302,8 @@ export class UserListComponent extends BaseListViewComponent<ViewUser> implement
         const choices = [_('add group(s)'), _('remove group(s)')];
         const selectedChoice = await this.choiceService.open(content, this.groupRepo.getViewModelList(), true, choices);
         if (selectedChoice) {
-            for (const user of this.selectedRows) {
-                const newGroups = [...user.groups_id];
-                (selectedChoice.items as number[]).forEach(newChoice => {
-                    const idx = newGroups.indexOf(newChoice);
-                    if (idx < 0 && selectedChoice.action === choices[0]) {
-                        newGroups.push(newChoice);
-                    } else if (idx >= 0 && selectedChoice.action === choices[1]) {
-                        newGroups.splice(idx, 1);
-                    }
-                });
-                await this.repo.update({ groups_id: newGroups }, user);
-            }
+            const action = selectedChoice.action === choices[0] ? 'add' : 'remove';
+            await this.repo.bulkAlterGroups(this.selectedRows, action, selectedChoice.items as number[]);
         }
     }
 
diff --git a/openslides/users/views.py b/openslides/users/views.py
index 3f8caf3cc..ddd2206ef 100644
--- a/openslides/users/views.py
+++ b/openslides/users/views.py
@@ -82,6 +82,7 @@ class UserViewSet(ModelViewSet):
             "bulk_generate_passwords",
             "bulk_reset_passwords_to_default",
             "bulk_set_state",
+            "bulk_alter_groups",
             "bulk_delete",
             "mass_import",
             "mass_invite_email",
@@ -246,6 +247,40 @@ class UserViewSet(ModelViewSet):
 
         return Response()
 
+    @list_route(methods=["post"])
+    def bulk_alter_groups(self, request):
+        """
+        Adds or removes groups from given users. The request user is excluded.
+        Expected data:
+        {
+            user_ids: <list of ids>,
+            action: "add" | "remove",
+            group_ids: <list of ids>
+        }
+        """
+        user_ids = request.data.get("user_ids")
+        self.assert_list_of_ints(user_ids)
+        group_ids = request.data.get("group_ids")
+        self.assert_list_of_ints(group_ids, ids_name="groups_id")
+
+        action = request.data.get("action")
+        if action not in ("add", "remove"):
+            raise ValidationError({"detail": "The action must be add or remove"})
+
+        users = User.objects.exclude(pk=request.user.id).filter(pk__in=user_ids)
+        groups = list(Group.objects.filter(pk__in=group_ids))
+
+        for user in users:
+            if action == "add":
+                user.groups.add(*groups)
+            else:
+                user.groups.remove(*groups)
+            # Maybe some group assignments have changed. Better delete the restricted user cache
+            async_to_sync(element_cache.del_user)(user.pk)
+
+        inform_changed_data(users)
+        return Response()
+
     @list_route(methods=["post"])
     def bulk_delete(self, request):
         """
@@ -357,13 +392,13 @@ class UserViewSet(ModelViewSet):
             {"count": len(success_users), "no_email_ids": user_pks_without_email}
         )
 
-    def assert_list_of_ints(self, ids):
+    def assert_list_of_ints(self, ids, ids_name="user_ids"):
         """ Asserts, that ids is a list of ints. Raises a ValidationError, if not. """
         if not isinstance(ids, list):
-            raise ValidationError({"detail": "user_ids must be a list"})
+            raise ValidationError({"detail": f"{ids_name} must be a list"})
         for id in ids:
             if not isinstance(id, int):
-                raise ValidationError({"detail": "every id must be a int"})
+                raise ValidationError({"detail": "Every id must be a int"})
 
 
 class GroupViewSetMetadata(SimpleMetadata):
diff --git a/tests/integration/users/test_viewset.py b/tests/integration/users/test_viewset.py
index c6465c292..ed4a2f5fc 100644
--- a/tests/integration/users/test_viewset.py
+++ b/tests/integration/users/test_viewset.py
@@ -9,7 +9,12 @@ from openslides.users.models import Group, PersonalNote, User
 from openslides.utils.autoupdate import inform_changed_data
 from openslides.utils.test import TestCase
 
-from ...common_groups import GROUP_DEFAULT_PK, GROUP_DELEGATE_PK, GROUP_STAFF_PK
+from ...common_groups import (
+    GROUP_ADMIN_PK,
+    GROUP_DEFAULT_PK,
+    GROUP_DELEGATE_PK,
+    GROUP_STAFF_PK,
+)
 from ..helpers import count_queries
 
 
@@ -421,6 +426,80 @@ class UserBulkSetState(TestCase):
         self.assertTrue(User.objects.get().is_committee)
 
 
+class UserBulkAlterGroups(TestCase):
+    """
+    Tests altering groups of users.
+    """
+
+    def setUp(self):
+        self.client = APIClient()
+        self.client.login(username="admin", password="admin")
+        self.admin = User.objects.get()
+        self.user = User.objects.create(username="Test name apfj31fa0ovmc8cqc8e8")
+
+    def test_add(self):
+        self.assertEqual(self.user.groups.count(), 0)
+        response = self.client.post(
+            reverse("user-bulk-alter-groups"),
+            {
+                "user_ids": [self.user.pk],
+                "action": "add",
+                "group_ids": [GROUP_DELEGATE_PK, GROUP_STAFF_PK],
+            },
+            format="json",
+        )
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertEqual(self.user.groups.count(), 2)
+        self.assertTrue(self.user.groups.filter(pk=GROUP_DELEGATE_PK).exists())
+        self.assertTrue(self.user.groups.filter(pk=GROUP_STAFF_PK).exists())
+
+    def test_remove(self):
+        groups = Group.objects.filter(
+            pk__in=[GROUP_DEFAULT_PK, GROUP_DELEGATE_PK, GROUP_STAFF_PK]
+        )
+        self.user.groups.set(groups)
+        response = self.client.post(
+            reverse("user-bulk-alter-groups"),
+            {
+                "user_ids": [self.user.pk],
+                "action": "remove",
+                "group_ids": [GROUP_DEFAULT_PK, GROUP_STAFF_PK],
+            },
+            format="json",
+        )
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertEqual(self.user.groups.count(), 1)
+        self.assertTrue(self.user.groups.filter(pk=GROUP_DELEGATE_PK).exists())
+
+    def test_no_request_user(self):
+        self.assertEqual(self.admin.groups.count(), 1)
+        self.assertEqual(self.admin.groups.get().pk, GROUP_ADMIN_PK)
+        response = self.client.post(
+            reverse("user-bulk-alter-groups"),
+            {
+                "user_ids": [self.admin.pk],
+                "action": "add",
+                "group_ids": [GROUP_DELEGATE_PK],
+            },
+            format="json",
+        )
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertEqual(self.admin.groups.count(), 1)
+        self.assertEqual(self.admin.groups.get().pk, GROUP_ADMIN_PK)
+
+    def test_invalid_action(self):
+        response = self.client.post(
+            reverse("user-bulk-alter-groups"),
+            {
+                "user_ids": [self.admin.pk],
+                "action": "invalid",
+                "group_ids": [GROUP_DELEGATE_PK],
+            },
+            format="json",
+        )
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+
+
 class UserMassImport(TestCase):
     """
     Tests mass import of users.