Slepton Flavour Mixing and Neutrino Masses

It is pointed out that important contribution to neutrino masses and mixing can come from flavour violating slepton exchange. For low and intermediate $\tan \beta$ such effects can dominate over the usual tau Yukawa coupling effects included in the renormalization group evolution. The mixing angles satisfy then the relation different from the fixed point solution of the renormalization group equation, and the desired neutrino mass splitting can be generated.