  We consider the problem of neutrino masses and mixing within the framework of
a non-minimal supersymmetric SU(5) model extended by adding a set of 1,24
chiral superfields accommodating three right-handed neutrinos. A Type I+III
see-saw mechanism can then be realized giving rise to a hierarchical mass
spectrum for the light neutrinos of the form m_3> m_2>> m_1 consistent with
present data. The extra colored states are pushed to the unification scale by
proton stability constraints, while the intermediate see-saw energy scale and
the unification scale are maintained in phenomenologically acceptable ranges.
We also examine the issue of large neutrino mixing hierarchy \theta_{23}>
\theta_{12}>> \theta_{13} in the above framework of hierarchical neutrino
masses.
