// Create a new instance of an XML Web service proxy class. SecureWebService s = new SecureWebService(); // Create the Authentication SOAP header and set values. Authentication a = new Authentication(); a.User = user.Value; a.Password = password.Value; // Assign the Header. s.AuthenticationValue = a; string result = s.ValidUser(); span1.InnerHtml = result;I think you will have to inspect your proxy class code to replace that Authentication() call with the one that the web service defines. There is a SoapHeader framework class that you have to work with.