Because an XASession is supposed to be transactional and it's transactonal state transitions are supposed to be determined by the transaction manager invoking methods on it's XAResource. JBoss MQ is adding an extra semantic by saying, as well as the above, if the XASession is not enlisted in any transaction it should act non transactionally. This is not a semantic of the XASession as specified in the JMS spec. As an analogy, if you obtained an XA database connection from Oracle but forgot to enlist it in a transaction, then did some database operations, you would be suprised if you discovered it had gone into auto commit mode. But that is exactly what you are expecting a jms xa connection to do. To me that seems counter intuitive (and possibly dangerous). View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3968749#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...