A baud rate detection system and method automatically detects the baud rate at which a client computing device is communicating with a host computer over a serial connection. The host computer is coupled to the client computing device via a serial connection, which employs a Unimodem null serial protocol. The baud rate detection system includes a baud rate selector to select among multiple baud rates that the client computing device might use to transmit a predefined message (e.g., a text string "C", "L", "I", "E", "N", "T"). The system also includes a message detector to listen at the currently selected baud rate for the predefined message. If the message detector receives the message, the current baud rate is the correct rate and is used for continuing communications with the client computing device. On the other hand, if the message detector fails to detect the message after a predetermined time period or detects characters not included in the predefined message, the baud rate selector chooses a new baud rate and the message detector begins listening at the new baud rate. This process continues until the baud rate detection system finds the appropriate baud rate for communicating with the client computing device.