i use primitives, seems to make the most sense (since its a primary key, its can't be nullable, so using larger Object representation doesn't seem necessary). Some people don't like setting the primitive int to "0" to indicate the ID isn't set - if you are one of those people, use Integer so you can set it to null to indicate the primary key isn't set yet. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4104795#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...