i do what you say because i need it. I have a many to many relation beetwen "puerto" and "ruta" and the pks in these classes(idRuta and idPuerto) are the composite pk in the "rutapuerto" entity and also they are fks referencing puerto and ruta. This is Database Theory but what can i do to this in EJB3? if i can´t find a solution i will use ManytoMany annotation creating a new table with it and i will use two lists, but how can i aggregate a new field with this annotation, and before find a entity in the table. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4042987#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...