Hi Felix, Success! Firstly apologies, I wrote "many-to-one" in my post. It is actually OneToMany (was quite late when I was writing ;) On my collection I had specified CascadeType.ALL which includes CascadeType.REFRESH. @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "order") | public Set<Address> getAddresses() { | return this.addresses; | } Changing this to exclude REFRESH worked a treat! @OneToMany(cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REMOVE}, fetch = FetchType.LAZY, mappedBy = "order") | public Set<Address> getAddresses() { | return this.addresses; | } All my entities are code generated, which I suppose makes it easy to overlook some of the finer details. Thanks for your help - greatly appreciated. Chris. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4046034#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...