Which version of Hibernate do you use? How have you packaged the hibernate jar in the EAR (where is it placed)? Please post the complete exception stacktrace that you see. Also, when Hibernate session factory gets built, it prints out the version of Hibernate being used. Something like: | 12:47:51,714 INFO [Version] Hibernate EntityManager 3.2.1.GA | 12:47:51,761 INFO [Version] Hibernate Annotations 3.2.1.GA | 12:47:51,776 INFO [Environment] Hibernate 3.2.4.sp1 What do you see in your case? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4142257#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...