Thanks for your response Felix, You earned me a new point of view to Entity Hierarchy in EJB3. I studied today this subject and found that JOINED strategy is an alternative way for entities annotated with @SecondaryTable or used @OneToOne relationship. You just need to derive a class from its parent and you will have an acces to all attributes from secondary table or from table with one-to-one ralationship in single entity. But I still can say nothing about differences between removing entities implemented hierarchy and @SecondaryTable or @OneToOne annotations. -- rustam bogubaev View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4041714#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...