The brake actuation device of a motor vehicle brake system includes a pneumatic brake booster 1, the interior of which is subdivided into at least one vacuum chamber and one working chamber, a master brake cylinder 2 and a pneumatic motor-and-pump assembly 3 for providing the vacuum in the vacuum chamber, which has a vacuum pump 6 and a motor 7 driving the vacuum pump 6. A vacuum level in the vacuum chamber or a difference in pressure between the vacuum chamber and the working chamber is sensed using a sensor 9, and the motor-and-pump assembly 3 is enabled by an electronic control unit 12 when the vacuum falls below a first defined bottom vacuum level Pe in the vacuum chamber and is disabled when a second defined top vacuum level Pa is reached.The rotational speed np of the motor-and-pump assembly 3 is controlled depending on driving conditions of the vehicle.