Nine rocks from the Alps (Aiguilles-Rouges, Mont-Blanc and Grand-Paradis massif, zone of Sesia-Lanzo) have been dated using the potassium/argon method. The results obtained in the latter area are in good agreement with currently held geological opinion. The ages found in the Aiguilles-Rouges and Mont-Blanc massifs are generally too young, indicating loss of argon. It is suggested that this loss of argon may be explained by accelerated diffusion rates due to hydrothermal and metamorphic processes which operated during the Alpine orogenesis and possibly the Saale phase of the Hercynian orogenesis. The size of the minerals used for dating appears to have an influence upon the ages obtained. The age found for the Grand-Paradis massif is somewhat older than that assigned to the Alpine orogenesis: two possible explanations of this disagreement are presented. Finally, the use of other methods, namely the Rb/Sr and Pb methods, is suggested to help resolve geochronometrical problems in the Alps.