  U(1)-family symmetries have led to successful predictions of the fermion mass
spectrum and the mixing angles of the hadronic sector. In the context of the
supersymmetric unified theories, they further imply a non-trivial mass
structure for the scalar partners, giving rise to new sources of flavour
violation. While tau->mu gamma decays are mostly expected to arise at rates
significantly smaller than the current experimental limits, the mu -> e gamma
rare decays impose important bounds on the model parameters. Even if universal
soft-terms are assumed at the GUT scale, when massive neutrinos are included in
these theories, new mixings appear in the soft-terms. The predicted branching
ratios for rare decays are in this case below the experimental bounds.
