 
 				req.requestHeaders.push(new URLRequestHeader("Content-Type", 'multipart/form-data; boundary=' + boundary));
 
-				// Add header
+				// Append mutlipart parameters
+				for (var name:String in postvars) {
+					multipartBlob.writeUTFBytes(
+						dashdash + boundary + crlf +
+						'Content-Disposition: form-data; name="' + name + '"' + crlf + crlf + 
+						postvars[name] + crlf
+					);
+				}
+
+				// Add file header
 				multipartBlob.writeUTFBytes(
 					dashdash + boundary + crlf +
 					'Content-Disposition: form-data; name="file"; filename="' + this._fileName + '"' + crlf +

						chunks = 4;
					}

					uploadNextChunk(multipart, chunk, chunks, chunkSize);
				}
			});


				// Add file data
				multipartBlob.writeBytes(chunkData, 0, chunkData.length);

				// Add file footer
				multipartBlob.writeUTFBytes(crlf + dashdash + boundary + dashdash + crlf);
				req.data = multipartBlob;
			} else {
