A method of and apparatus for preventing data destruction in a multiplex communication system. The invention is useful in a bit serial scheme to prevent transmission data from being destroyed by collision caused by the time delay in transmission data between transmitter and receiver. After sending transmission data, a transmitter starts a transmission clock when a receiver has received the data. When the received data has become non-priority, the receiver resets the reception clock. The transmitted data is compared with the received data, and the transmission is stopped whenever a mismatch is detected. In addition, a non-prioritized bit signal is provided after the unit address for determining transmission priority in the above-mentioned transmission data format. The invention is useful in preventing data destruction in a vehicle control system, which controls the operation of a plurality of units mounted on a vehicle, e.g. an ABS system, a vehicle speed sensor, a cam pulser, and other vehicle systems.