Are you calling the EJBs using the "remote interface" of the EJBs? As per the EJB3 Core specification 3.2.1, the parameters and return types are passed by value (which means that any changes to the parameters inside the bean will not be visible to the caller): anonymous wrote : 3.2.1 Remote Clients | | The arguments and results of the methods of the remote business interface are passed by value. Use the "local interface" to invoke the bean methods to pass the objects by reference. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4157227#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...