Thanks. But what I need is a unique constraint on multiple columns, including columns that are foreign keys. Anyway, I solved my problem by using the attribute "name" of the JoinColumn annotation instead of the property name. @javax.persistence.Table( | name = "UNITE_EMPLOYE", | uniqueConstraints = { | @javax.persistence.UniqueConstraint(columnNames = {"EMPLOYE_FK", "NOEUD_ORGANISATION_FK"})}) | What is strange is that in the Hibernate documentation, it is said : anonymous wrote : The @Table element also contains a schema and a catalog attributes, if they need to be defined. You can also define unique constraints to the table using the @UniqueConstraint annotation in conjunction with @Table (for a unique constraint bound to a single column, refer to @Column). | | @Table(name="tbl_sky", | uniqueConstraints = {@UniqueConstraint(columnNames={"month", "day"})} | ) | | A unique constraint is applied to the tuple month, day. Note that the columnNames array refers to the logical column names. Am I wrong when I think that logical column name is the property name of the entity bean ? Or maybe there's a difference between Hibernate and EJB3 entities about this ? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4095104#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...