A method for hardening running surfaces of roller bearing components, in particular outer bearing rings. In order to provide the edge area (functional layer) of the roller bearing components with a deep layer which is particularly hard and resistant to corrosion, the roller bearing component undergoes nitration for a long period of time at a temperature of between 450 and 650° C. for at least 25 hours. During treatment no carburizing and subsequently no quenching takes place.