an anti - skid control system for a motor vehicle in which , when a wheel speed to be controlled and being decreased through buildup of brake pressure becomes equal to a reference speed , this equality is judged as a fulfillment of a brake pressure reduction starting condition , and thus reduction of the brake pressure is started . the highest wheel speed is detected and a computed vehicle speed is set up based on the highest wheel speed by having the increase and decrease of the highest wheel speed limited to a predetermined range . the computed vehicle speed and the wheel speed to be controlled are compared ; and when the comparison indicates that the wheel speed to be controlled is equal to or higher than the computed vehicle speed , no reduction of the brake pressure is started irrespective of whether the brake pressure reduction starting condition is fulfilled .