A model of formation and development of local plastic strain regions is proposed on the basis of an analysis of the main physical processes taking place in a metallic material under the action of cyclic loads. An equation of material state for the instant of time directly preceding fatigue crack initiation has been derived, in which cyclic loading frequency in explicit form as a factor directly affecting the damage accumulation rate and stress ratio are taken into account. The equation is the basis for the prediction of fatigue resistance characteristics, large loading bases as well, at different frequencies, including low ones, from high-frequency test data.