  We review models where R-parity is broken, either spontaneously or
explicitly. In this last case we consider the situation where R-parity is
broken via bilinear terms in the superpotential. We show that although at tree
level only one neutrino gets mass, at one--loop level all three neutrinos
became massive. We study the conditions under which bimaximal mixing can be
achieved and show that the masses can be in the correct ranges needed for
solving the atmospheric and solar neutrino problems.
