I've just run into this problem again and am posting back here so I don't forget again. When trying to delete an entity that has existing relationships (eg. OneToMany) you have to ensure that you clear the collection before removing the object. eg:public void deleteGroup(Group group) { | | //where the relationship btw a 'User' and a 'Group' is maintained in a 'UserGroupList' | | group.getUserGroupLists().clear(); | entityManager.remove(group); | } Cheers, Damian. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4116092#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...