Yes, that's what I expected (that connections are stored in the tx). Hibernate (EJB3) is the one requesting the connection. I am not doing this explicitly there. I might open a connection from the same DS explicitly in another place (within this tx) and then call close() when done. But that should be fine I guess. Of course all work is done in one big tx. It is opened via a UserTransaction from a BMT session bean. The problem occurs before the call returns to the bean that started the tx. Maybe there is a bug in an interceptor, so the tx is lost in the TransactionLocale? Anyway, yes we are drifting away from the problem. I still think it is perfectly legal to open as many connections as I like even if the current tx is set rollback-only. I guess the rollback-only flag is only set in the transaction manager and the connection is completely unaware of this fact until the transaction manager performs the rollback at the end. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4104552#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...