A numerical analysis is performed of the effect of cyclic pre-loading regime on the posterior hydrogen assisted cracking behaviour of high-strength steel, considering mechanical items (stress-strain evolution) and chemical aspects (hydrogen diffusion). With regard to mechanical issues, a high resolution numerical modelling is carried out of the elastoplastic stress-strain field in the near-tip area under cyclic loading (to simulate fatigue pre-cracking) and posterior monotonie loading (to simulate a slow strain rate test), considering the role of large near-tip deformations. In the matter of chemical aspects, a quantitative modelling of hydrogen diffusion is performed near the crack tip, accounting for the transient stress-strain field that evolves from the compressive one after precracking to the tensile one during the test. Results show that hydrogen accumulation in fracture sites depends on residual stress distributions produced by cyclic pre-loading.