As far as i know, JBoss does not look in the META-INF folder for the persistence.xml file. The documentation at http://docs.jboss.org/ejb3/app-server/reference/build/reference/en/html/e... says this: anonymous wrote : | 3.2.2. persistence.xml and .jar files | | Entities are placed in a EJB-JAR .jar file or a .jar file all their own. You must also define a persistence.xml file that resides in the META-INF folder of the .jar file. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4139311#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...