diff --git a/modules/fbs-core/web/src/app/dialogs/group-deregister-dialog/group-deregister-dialog.component.ts b/modules/fbs-core/web/src/app/dialogs/group-deregister-dialog/group-deregister-dialog.component.ts
index ff6756b5d..7367c494d 100644
--- a/modules/fbs-core/web/src/app/dialogs/group-deregister-dialog/group-deregister-dialog.component.ts
+++ b/modules/fbs-core/web/src/app/dialogs/group-deregister-dialog/group-deregister-dialog.component.ts
@@ -1,11 +1,12 @@
 import { Component, Inject, OnInit } from "@angular/core";
-import { Observable } from "rxjs";
+import { Observable, combineLatest } from "rxjs";
 import { GroupRegistrationService } from "../../service/group-registration.sevice";
 import { MAT_DIALOG_DATA, MatDialogRef } from "@angular/material/dialog";
 import { Participant } from "../../model/Participant";
 import { Group } from "../../model/Group";
 import { GroupService } from "../../service/group.service";
 import { CourseRegistrationService } from "../../service/course-registration.service";
+import { map } from "rxjs/operators";
 
 @Component({
   selector: "app-group-deregister-dialog",
@@ -40,8 +41,22 @@ export class GroupDeregisterDialogComponent implements OnInit {
 
   loadMembers(): void {
     if (this.data.adding) {
-      this.members$ = this.courseRegistrationService.getCourseParticipants(
-        this.data.cid
+      const courseMembers$ =
+        this.courseRegistrationService.getCourseParticipants(this.data.cid);
+      const groupMembers$ = this.groupRegistrationService.getGroupParticipants(
+        this.data.cid,
+        this.data.gid
+      );
+
+      this.members$ = combineLatest([courseMembers$, groupMembers$]).pipe(
+        map(([courseMembers, groupMembers]) =>
+          courseMembers.filter(
+            (courseMember) =>
+              !groupMembers.some(
+                (groupMember) => groupMember.user.id === courseMember.user.id
+              )
+          )
+        )
       );
     } else {
       this.members$ = this.groupRegistrationService.getGroupParticipants(