The kinetics of decomposition of supercooled austenite of medium-carbon Cr - Ni - Mo steels in the pearlite range is studied by dilatometric and metallographic methods with computer processing of the data. It is shown that the rate of the decomposition of supercooled austenite in the pearlite range oscillates with a low amplitude. The changes in the exponent in the Avrami and Ostin - Rikket equations that describe the decomposition of supercooled austenite are associated with simultaneous processes of austenitic transformation whose kinetics differs substantially in local regions of the metal, which is mainly connected with the polymodal nature of the grain structure of the austenite.