A serial port interface is a Graphical User Interface program that runs on a personal computer and can be used to connect to a microcontroller via a serial connection. In this article a detailed step by step description with source code on how to create a simple Serial Port Graphical User Interface (GUI) using Microsoft Visual C# is outlined. From the toolBox on the left-hand side, under the Components sub-section, drag and drop SerialPort Control on the form and it shall appear below it. This control will enable us to send or receive data through the COM Port (Serial port) of the PC.