 <p>This problem is not specific to Entity Framework (although EF certainly also has other limitations around UNIQUE constraints). This is common with any similar server-client model. Since the uniqueness will be enforced by the database server at the time of the request, there is no fool-proof way to know in advance if the constraint will be violated, until you attempt the insert.</p> <p>That said, checking for uniqueness in advance should be a very cheap operation (on SQL Server, a UNIQUE constraint will also give you an index on that column), so depending on how often you expect the application to be attempting duplicate insertion, this should cover the large majority of your cases. But if the duplicate insert attempts would be quite rare to begin with, you can avoid making the extra round-trip per insert and just handle the exception when it happens.</p> <p>Handling the exception doesn't need to be very complicated, especially if there is a way for the end user to modify the data and attempt a retry. In the case where, as you said, you're queuing-up several inserts in a single transaction, you may need to check the exception (or inner exception) for specific constraint names, so that you know which entity object is a duplicate. (Again, EF doesn't really support handling UNIQUE constraint exceptions directly, so this is probably the part that is causing you the most pain right now.)</p> <p><strong>Note:</strong> I would not recommend re-working the insert as a stored procedure just to circumvent the rare chance that duplicate entries get attempted concurrently. You're better off making sure your application handles this (and other SQL exceptions, of which there may be many) as gracefully as possible. However, if you are finding that in your case there is really no other way, a sproc may be the easiest approach for now. Just keep in mind that it's probably foregoing more maintainable code in order to solve a very rare edge case.</p>