In case the MDB uses some entity beans and this process is using CMT, this message will be displayed on the Server Output(If the transaction level is 'NotSupported' the message is not displayed): "[LocalTxConnectionManager$LocalConnectionEventListener] prepare called on a local tx. You are not getting the semantics you expect!" It means there is more than one participant in a transaction where at least one of the participants only supports local (1pc, non xa) transactions. Failures during the commit process will result in inconsistent results. This is most likely to happen if you use jms and db access in the same tx. Ok, my question is how can I use the entity beans inside a MDB's onMessage() method and not get this warning message? Thanks for your ideas.