A hybrid drive train of a motor vehicle which comprises a combustion engine, an electric machine which is operable as a motor and a generator and comprises a stator and a rotor, and a multi-stage planetary transmission with input and output shafts. The driveshaft of the combustion engine can be connected to the input shaft of the transmission, the electric machine is coaxially arranged about the input shaft, and the rotor of the electric machine is rigidly connected with the input shaft. To achieve a starting acceleration and climbing capacity on starting, corresponding to those provided by a drive train with an automatic transmission and a hydrodynamic torque converter or a manual gearshift transmission with a converter shifting clutch, the rotor of the electric machine can be connected with the transmission input shaft via an input transmission stage which is formed as a simple planetary gearset and has a high gear ratio.