For starters, here's my code: // Create a request using a URL that can receive a post. WebRequest request = WebRequest.Create("http://mydomain.com/cms/csharptest.php"); request.Credentials = new NetworkCredential("myUser", "myPass"); // Set the Method property of the request to POST. request.Method = "POST"; // Create POST data and convert it to a byte array. string postData = "name=PersonName&age=25"; byte[] byteArray = Encoding.UTF8.GetBytes(postData); // Set the ContentType property of the WebRequest. request.ContentType = "application/x-www-form-urlencoded"; // Set the ContentLength property of the WebRequest. request.ContentLength = byteArray.Length; // Get the request stream. Stream dataStream = request.GetRequestStream(); // Write the data to the request stream. dataStream.Write(byteArray, 0, byteArray.Length); // Close the Stream object. dataStream.Close(); // Get the response. HttpWebResponse response = (HttpWebResponse)request.GetResponse(); // Display the status. Console.WriteLine((response).StatusDescription); // Get the stream containing content returned by the server. dataStream = response.GetResponseStream(); // Open the stream using a StreamReader for easy access. StreamReader reader = new StreamReader(dataStream); // Read the content. string responseFromServer = reader.ReadToEnd(); // Display the content. Console.WriteLine(responseFromServer); // Clean up the streams. reader.Close(); dataStream.Close(); response.Close(); The directory cms/ requires authentication, but if I try running this same code somewhere, where authentication isn't needed, it works fine. The error (System.Net.WebException: The remote server returned an error: (403) Forbidden) occurs at HttpWebResponse response = (HttpWebResponse)request.GetResponse(); I have managed in reading data after authenticating, but not if I also send POST data. What's wrong with this?