Abstract Cyclic deformation of f.c.c. metals leads to intergranular cracks even at low plastic strain amplitudes. Experimental observations indicate that most of these cracks are formed by the action of persistent slip bands against grain boundaries at the surface. Theoretical considerations are presented allowing an estimate of the dependence of the crack frequency distribution (with respect to characteristic angles) on the environment and the magnitude of the plastic strain range Δϵpl. The theoretical results are compared with experimental observations on crack initiation carried out on polycrystalline copper fatigued in air and in vacuum at different Δϵpl.