A method of operating a drive-train of a motor vehicle having a hybrid drive with an internal combustion engine and an electric machine, an electrical energy accumulator that can be charged when the electric machine operates as a generator and discharged when the electric machine operates as a motor, a transmission connected between the hybrid drive and a drive output, and at least one auxiliary power takeoff on either the transmission or the hybrid drive side such that the auxiliary power takeoff can be operated with variable energy demand within functional capability limits that depend on the auxiliary power takeoff. Depending on the current operating status of the hybrid drive unit, the electrical energy accumulator and/or the auxiliary power takeoff, energy available in the drive-train, but not required at the drive output, can bypass the electrical energy accumulator and be stored in the auxiliary power takeoff.