Abstract The surface nucleation of misfit dislocations in vicinal (001)-oriented heterostructures is discussed. It is shown that beside the asymmetrical stressing of opposite dislocation slip planes due to the vicinal substrate, the surface steps have a similar effect. The effect of the steps has the same-sign asymmetry for a compressive stressed epilayer, but is opposite in the tensile case. The effect on dislocation nucleation energy is calculated. For miscut angles used normally, the step energy contribution exceeds that due to the vicinal substrate. The effect on epilayer tilting is also discussed.