A method for operating a drive train of a motor vehicle is provided, the drive train featuring a first drive assembly formed as an internal combustion engine a second drive assembly formed as an electric motor, a start-up element and a transmission). The start-up element features a converter and a lock-up clutch and is connected between the electric motor and the transmission. The electric motor is connected between the internal combustion engine and the start-up element. If a decoupling of the lock-up clutch is requested, the lock-up clutch of the start-up element is initially brought into slip. If the slip at the lock-up clutch of the start-up element reaches a threshold or is greater than the threshold, a target rotational speed is subsequently predetermined for the electric motor and the rotational speed of the electric motor is adjusted to such target rotational speed.