Using results of the band structure calculations in the local-spin-den
sity approximation, we demonstrate how the crystal distortions affect
the magnetic structure of orthorhombically distorted perovskites leadi
ng to a non-collinear spin arrangement. Our results suggest that the n
on-collinearity of the spin magnetic moments, being generally small in
LaMO3 series with M = Cr-Fe, is large in SrRuO3.