 <p>No, <code>AsyncPattern</code> is no longer required as of .NET 4.5.</p> <p>I have a blog post <a href="http://blog.stephencleary.com/2012/08/async-wcf-today-and-tomorrow.html">Async WCF Today and Tomorrow</a> that compares the old way of asynchronous WCF ("Today" in the blog post: .NET 4.0) with the new way of asynchronous WCF ("Tomorrow" in the blog post: .NET 4.5).</p>