I also have observed this leak, take a look at this topic: http://www.jboss.org/index.html?module=bb&op=viewtopic&t=84255 As far as I observed, the leak is caused by the following sequence of operations: - querying server for entities and obtaining them via rmi to the remote java client - constucting new entity having collection of those detached entities on the client side - sending object with the collection to the server and persisting it (detached entities are reloaded into current session with EntityManager.find() or getReference) Pawel Miniewicz View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3975756#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...