 <p>You'll probably need to define a custom MessageContract for this operation. Check out the following link, specifically the section on "Using Arrays Inside Message Contracts" and the MessageHeaderArrayAttribute.</p> <p><a href="http://msdn.microsoft.com/en-us/library/ms730255.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/ms730255.aspx</a></p>