Based on the determination of the damage accumulation in the cyclic-plastically deformed zone at the tip of a propagating crack, a model for the propagation of fatigue cracks in ductile media was derived. The model establishes a relationship between the rate of propagation of fatigue cracks and the parameters that determine the load, test specimen shape, crack length and the cyclic-plastic and fracture properties of the material. Good agreement of the experimental results with the proposed model for fatigue crack propagation in steels is noted.