As i suspected, the logs show no indication that the "Account" entity is being mapped. For example, when i deploy my sample application with entities, i see this on the console: 8:18:47,998 INFO [JmxKernelAbstraction] jboss.jca:name=EJB3PersistenceDS,service=DataSourceBinding | 8:18:47,998 INFO [PersistenceUnitDeployment] Starting persistence unit persistence.units:ear=EJB3Persistence.ear,jar=myapp_ejb3.jar,unitName=EJB3Persistence | 8:18:48,060 INFO [Version] Hibernate EntityManager 3.2.1.GA | 8:18:48,107 INFO [Version] Hibernate Annotations 3.2.1.GA | 8:18:48,123 INFO [Environment] Hibernate 3.2.4.sp1 | 8:18:48,138 INFO [Environment] hibernate.properties not found | 8:18:48,138 INFO [Environment] Bytecode provider name : javassist | 8:18:48,138 INFO [Environment] using JDK 1.4 java.sql.Timestamp handling | ..... | | 8:18:48,857 INFO [AnnotationBinder] Binding entity from annotated class: org.myapp.entity.User | 8:18:48,935 INFO [EntityBinder] Bind entity org.myapp.entity.User on table User | 8:18:49,467 INFO [AnnotationBinder] Binding entity from annotated class: org.myapp.entity.Account | 8:18:49,467 INFO [EntityBinder] Bind entity org.myapp.entity.Account on table Account | 8:18:49,482 INFO [AnnotationBinder] Binding entity from annotated class: org.myapp.entity.TestIdClass | 8:18:49,513 INFO [EntityBinder] Bind entity org.myapp.entity.TestIdClass on table EJB3Test | 8:18:49,529 INFO [AnnotationBinder] Binding entity from annotated class: org.myapp.entity.DeleteMe | 8:18:49,529 INFO [EntityBinder] Bind entity org.myapp.entity.DeleteMe on table DELETEME | 8:18:49,560 INFO [CollectionBinder] Mapping collection: org.myapp.entity.User.accounts -> Account | 8:18:50,185 INFO [ConnectionProviderFactory] Initializing connection provider: org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider | 8:18:50,201 INFO [InjectedDataSourceConnectionProvider] Using provided datasource | 8:18:50,654 INFO [SettingsFactory] RDBMS: MySQL, version: 5.0.20-community It looks like a packaging problem. anonymous wrote : The Account.class is part of the DAO and is in datamodel.jar while the other classes are in another services.jar file. I have packaged the persistence.xml in the META-INF of both jar. | Usually, the persistence.xml file should be present in only the jar which contains the entity classes. Try removing the persistence.xml file from the services.jar file (which i assume does not have any entities). View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4153936#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...