  Assuming three light neutrinos and the see-saw mechanism we present a
semiquantitative model of fermion masses based on (SUSY) SU(5) and abelian
horizontal charges. A good description of the observed pattern of quark and
lepton masses is obtained. For neutrinos we naturally obtain widely split
masses and large atmospheric neutrino mixing as a consequence of SU(5)-related
asymmetric mass matrices for d quarks and charged leptons.
