EntityManager.merge(Object) works too. persist is like an SQL INSERT merge is like an SQL INSERT/UPDATE View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4063051#4063051 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4063051