In a system for controlling a parking brake of a brake system of a motor vehicle, a first target value for the braking force of the parking brake is predefined by a operating element for the parking brake and the braking force for the parking brake is released by a operating element. When a start-up intention is detected, the control system minimizes the braking force of the parking brake in relation to the first target value, in accordance with the environmental conditions of the motor vehicle. For the first time a provisional minimization of the braking force of a parking brake for a foreseeable start-up situation is permitted, thus allowing the start-up operation of a motor vehicle to be as comfortable as possible with maximum security of the automatic functions. The system is particularly suitable for electromechanical parking brakes.