A method of actuating a retarder of a motor vehicle, for example a hydrodynamic retarder of a commercial vehicle, in which during overrun operation the driver uses an operating element to call for a braking action by the retarder. To implement the method simply, conveniently and inexpensively, the accelerator pedal of the motor vehicle is used as the operating element for demanding a braking action by the retarder. In such manner that when the torque of the drive engine of the motor vehicle becomes negative due to overrun operation, the braking action demand is signaled by at least partially releasing the accelerator pedal.