It is known that the fatigue process begins with plastic deformation of the surface layers of the reinforcement metal. Moreover, the movement of dislocations in the conditions of repeatedly alternating stresses is observed at loads below the elastic limit of the metal. The rate of local plastic deformation during cyclic deformation is several orders of magnitude higher than the rate of deformation under static loading. Slip of dislocations begins in grains with a favorable orientation near the stress concentrators. With an increase in the number of cycles in the surface layers, the density of dislocations and the number of vacancies increases. When the basic number of NR cycles is reached, a surface hardened metal layer is formed with a large number of seed cracks, the size of which does not reach a critical value. An increase in the number of cycles cannot cause further development of destruction in such a layer. Only when the stresses exceed the endurance limit do the cracks reach a critical length, after which the process of their draining into the main crack begins with the propagation of the latter. The results of experimental studies indicate a strong influence of diffusible hydrogen on the static and cyclic parameters of crack resistance. It was established that with the increase of flooding, especially when the hydrogen content exceeds 5 cm3100g, both the static strength and long-term strength (fatigue-laziness) decrease sharply. Moreover, these areas of the hydrogen solution in the reinforcing steel are characterized by a viscous nature of fracture, while for heavily flooded reinforcement (from 5 to 12 cm3100g, brittle fracture by the mechanism of micro-split in the hardened (martensitic or troostite structure) is inherent. The analysis of the obtained experimental results made it possible to determine the optimal content of hydrogen in reinforcing steel (3-5 cm3 100g), the excess of which will cause a decrease in the crack resistance of the reinforcement in the process of long-term operation, especially in corrosive and aggressive environments. The issue of fatigue of reinforcing steels is very relevant today.