I don't have the code in front of me, but I will post it when I get to the office. But I can describe it briefly as it's pretty standard. It's a basic MDB with container managed transactions. Withing my onMessage method, I am calling the entityManager repeatedly asking it to persist a large number of objects. From the links you sent it seems that the timeout of 300 seconds (default) could well be the cause of my problem. I will run some more tests tomorrow and get back to you. Thanks for the link to the information. Regards Alex View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4088232#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...