a method and an apparatus are described for monitoring a rotating synchronous electric machine , which comprises a rotor having a rotor winding and a stator having a stator winding . the method comprises the steps of determining the stator winding current , determining the stator winding voltage , determining the rotor winding current , and estimating the temperature in at least two positions in the electric machine using a model of the electric machine and the determined current and voltage values . an apparatus according to the invention is provided for carrying out the method .