In a method of operating a hybrid drive train for a motor vehicle including an internal combustion engine, an electric machine and a transmission, a first clutch arranged between the internal combustion engine and the transmission and the electric machine being arranged in parallel with the first clutch and being connectable to the internal combustion engine by way of a second clutch and to the transmission via a third clutch, the electric machine is connected by means of the second and third clutches to the internal combustion engine and to the transmission for assisting the first clutch transmitting an excessive engine torque, and upon failure of the first clutch, for starting movement of the motor vehicle, the third clutch is engaged and the electric machine is energized for transferring an electric machine torque to the transmission and the second clutch is engaged when the vehicle has reached a speed corresponding to the engine speed.