The invention relates to a method for operating a brake system for motor vehicles, comprising an electrically controllable pressure supply device (5) which is made of a cylinder/piston arrangement with at least one hydraulic pressure chamber (37), the piston (36) of the arrangement being displaceable by means of an electromechanical actuator (35). The brake system also comprises a number of wheel brakes (8, 9, 10, 11), each of which is connected to the pressure supply device (5) via an electrically actuatable inlet valve (6a-6b), and an electrically actuatable outlet valve (7a-7d) for at least one of the wheel brakes, said wheel brake being connectable to a pressure medium storage container (4) by means of the outlet valve. In a normal control mode (N) of the brake system, a displacement of the piston (36) of the pressure supply device (5) is terminated by outputting an actuation signal to the pressure supply device, and the inlet valves of the wheel brakes are closed in the event of a specified brake condition (A). The normal control mode is switched to a special control mode (S) in the event of a specified condition for the pressure supply device (B). In the event of the specified brake condition (A) in the special control mode, a displacement of the piston (36) of the pressure supply device (5) is terminated by outputting an actuation signal to the pressure supply device, and for at least one selected wheel brake (8, 9), the corresponding inlet valve (6a, 6b) is kept open and the corresponding outlet valve (7a, 7b) is opened at least temporarily while the inlet valves (6c, 6d) of the remaining wheel brakes (10, 11) are closed. The invention also relates to a brake system.