 <p>The Linq provider in NHibernate 2.x is very limited and it usually has problems with projections of entities.</p> <p>Your query probably works with the included Linq provider in NHibernate 3.x.</p> <p>HQL is easy:</p> <pre><code>select Sender from Enquiry where Created &lt; current_timestamp </code></pre> <p>(You can also use a parameter for DateTime.Now)</p>