Abstract: The invention relates to a method for monitoring the radial gap (10) between the rotor (6) and the stator (8) of an electric generator (2). The aim of the invention is to provide a method that allows an especially reliable analysis of the shape of the radial gap (10) during operation of the generator (2). To this end, a measuring cycle is carried out in the stationary and balanced operating mode of the generator at defined intervals. In every measuring cycle, current parameters (120) of the radial gap (10) are determined from current marginal values (50) of the generator (2), from current influential values (80) of the generator (2) and from current measuring data (100). These parameters are used to determine and evaluate the shape of the radial gap (10) and the distance between the rotor (6) and the stator (8) by comparing them with reference parameters. The inventive method allows to better predict when repairs have to be made.