Abstract: A deceleration indication system for use on motor vehicles to indicate to the trailing driver that the leading vehicle is decelerating thereby to prevent rear end collisions. The system is of the solid state type and is arranged to detect and respond to decrease in the rate of operation of the ignition system of a motor vehicle to light amber indication lamps at the rear of the vehicle. Since the speed of the vehicle is proportional to the rate of operation of its ignition system, these lamps will give an immediate indication to the trailing driver that the leading vehicle is decelerating thereby affording the trailing driver with more time for braking.