A method for synchronizing a rotation speed of a permanently excited rotor of an electric motor with a frequency of a rotation field of a sensorless commutated stator of the electric motor during a run-up procedure of the electric motor includes determining a phase position of the rotation field and a phase position of a countervoltage that is induced by the rotor in the stator in order to obtain a phase offset between the rotation field and the countervoltage. The method further includes adjusting a prevailing amplitude of one component of the rotation field using the phase offset to synchronize the rotation speed with the frequency. The amplitude of the component is increased if the rotor is lagging behind the rotation field or the amplitude of the component is reduced if the rotor is running ahead of the rotation field.