Sorry, forgot to quote.I have started a new system as well. And have started down the road of exposing my Business Model objects which are hibernate persistance objects to my service layer. The problem I see is whe you have lazy initialization. It just does not seem right to me that the service layer has an object which has an attribute called say itemList which is a set of Item objects. However, since the itemList is lazily initialized it can not access it without opening a transaction/session. It seems that your data access layer now creeps into your service layer, and your service layer now has to know that something is lazily initialized or eagerly fetched. I am at a cross roads now as to best implementation.