Abstract: A hydraulic brake system for automotive vehicles comprises a master cylinder (4) with at least two working chambers (3,5) and comprising at least two brake circuits. A first brake circuit is in constant hydraulic communication with a first working chamber (3) of the master cylinder (4), while a second brake circuit is connected to the second working chamber (5) of the master cylinder (4). A pressure control valve (1) is inserted into the connection between the working chamber (5) and the second brake circuit, the valve enabling to take influence on the pressure in the second brake circuit in a predeterminable fashion. The pressure control valve (1) is switchable by a slip monitoring electronics (62) so that braking pressure control in the second brake circuit will take place exclusively in the event of failure of the brake slip control apparatus.