In supersymmetric (SUSY) models the misalignment between fermion and sfermion families introduces unsuppressed flavour-changing processes. Even if the mass parameters are chosen to give no flavour violation, family dependent radiative corrections make this adjustment not stable. In particular, due to the observed large neutrino mixings and potentially large neutrino Yukawa couplings, sizable lepton flavour violation (LFV) is expected. After introducing the basic concepts, the framework and the main assumptions, we report on a recent study of rare leptonic decays in a class of SUSY--GUT models with three quasi-degenerate neutrinos. We show that LFV effects are likely visible in forthcoming experiments.

PACS numbers: 12.60.Jv, 13.35.--r, 14.60.Pq, 14.60.St