A brake system for motor vehicles of “brake-by-wire” type without a brake booster, having a hydraulic activation device which can be activated by means of a brake pedal and to which wheel brakes are connected, and a simulation device which can be activated hydraulically and has at least one elastic element which gives the driver of a vehicle a pleasant pedal sensation is intended to have a functional capacity which can be checked during the normal braking function and to give the driver a pedal sensation which is familiar from a conventional hydraulic brake system. For this purpose, the activation device is connected via a hydraulic connection to the simulation device, wherein the hydraulic connection is connected via an electrically controllable check valve to a pressure medium reservoir which is at atmospheric pressure.