Massive neutrinos and lepton-flavour-violating processes

If neutrino masses and mixings are suitable to explain the atmospheric and solar neutrino fluxes, this amounts to contributions to FCNC processes, in particular $\mu \to e,\gamma$. If the theory is supersymmetric and the origin of the masses is a see-saw mechanism, we show that the prediction for BR($\mu \to e,\gamma$) is in general larger than the experimental upper bound, especially if the solar data are explained by a large angle MSW effect, which recent analyses suggest as the preferred scenario.