Abstract: A method for operating a brake system of a vehicle which includes a master brake cylinder which can be activated by the driver by a brake pedal, at least one driver-independent pressure source, at least one wheel brake to which a wheel speed sensor is assigned, and a brake activation sensor, wherein it is checked whether a hazardous situation is present, and in the case of a hazardous situation being detected the at least one driver-independent pressure source is activated. A hazardous situation is detected when the change in a measured deceleration over time or the absolute value of a measured deceleration exceeds a predefined hazard threshold value and a brake activation operation is detected. In addition, the invention relates to a brake system for a motor vehicle having brake assistance in hazardous situations which does not require a master brake cylinder pressure sensor.