Small tilting of the epilayer lattice planes is commonly observed in l
attice-mismatched epilayers grown on vicinal substrates. This tilt is
commonly believed to be an alternative strain-relieving mechanism to t
he formation of misfit dislocations. It is shown that this is not like
ly for (100) heterosystems, because the introduction of those dislocat
ions is favorable which relax misfit rather than those which induce ti
lt. The model shows good agreement with experimental observations.