A method for operating a motor vehicle brake system having hydraulic wheel brakes; an atmospheric pressure pressure medium reservoir; a pressure modulation unit setting wheel-specific brake pressures, an electrohydraulic pressure provision device connected to the pressure modulation unit and the pressure medium reservoir which outputs brake system pressure to the pressure modulation unit and draws in pressure medium from the reservoir; a first and second pressure activation valve connecting the pressure provision device to the pressure modulation device. A piston of the piston-cylinder arrangement separates two pressure spaces from one another. A pressure build-up occurs in the first pressure space during a backward movement of the piston and in the second pressure space during a forward movement of the piston. During a brake pressure build-up by a forward stroke of the piston, the activation valve is opened and the first pressure space is hydraulically separated from the pressure medium reservoir.