A power brake system having electronic slip regulation, and a method for controlling a power brake system having electronic slip regulation. A return line is equipped with a pressure medium storage unit for storing pressure medium with a pressure that is greater than an ambient atmospheric pressure, and is equipped with a blocking device that is controllable and that is situated between the pressure medium storage device and the reservoir. In addition, there is a pressure medium connection between the pressure medium storage unit and the plunger working space. A controlling of a power brake system takes place using the blocking device in such a way that the return line is blocked relative to the reservoir as soon as a plunger piston, driven by a drive unit, has traveled a definable path in the forward direction.