An electronically adjustable brake operating system for vehicles is proposed, with a brake master cylinder (2) which can be operated by means of an operating pedal (1), with brake pressure transducers (4-6) which can be actuated by an electronic control unit (3), wheel brakes (8, 10) being connected directly to the brake pressure transducers which can be connected, via hydraulic lines (11, 12) which can be closed off by valve devices (16, 17), to the brake master cylinder (2). There is also at least one sensor device (22, 23) to detect the driver's wish to slow down, and at least one simulator chamber (14, 15) which co-operates with the brake master cylinder (2). As an improvement to systems of this type, especially during anti-lock operation, it is proposed according to the invention that the valve units should take the form of solenoid valves (16, 17) which can be actuated by the electronic control unit (3), and that the pressure-volume uptake characteristics of the simulator chamber (14, 15) should be independent of the wheel brakes (7, 8, 9, 10).