  Prospects for SO(10) as a minimal grand unification group have recently been
heightened by several considerations such as the MSW resolution of the solar
neutrino puzzle, baryogenesis, possibility for understanding fermion masses
etc. I review the present status of the minimal SO(10) models with special
emphasis on the predictions for proton lifetime and predictions for neutrino
masses for the non-supersymmetric case and discuss some preliminary results for
the supersymmetric case. It was generally believed that minimal SO(10) models
predict wrong mass relations between the charged fermions of the first and
second generations; furthermore, while the smallness of the neutrino masses in
these models arises from the see-saw mechanism, it used to be thought that
detailed predictions for neutrino masses and mixings require further adhoc
assumptions. In this talk, I report some recent work with K.S.Babu, where we
discovered that the minimal SO(10) model, both with and without SUSY, has in it
a built-in mechanism that not only corrects the bad mass relations between the
charged fermions but at the same time allows a complete prediction for the
masses and mixings in the neutrino sector. We define our minimal model as the
one that consists of the smallest set of Higgs multiplets that are needed for
gauge symmetry breaking. Our result is based on the hypothesis that the complex
{\bf 10} of Higgs bosons has only a single coupling to the fermions. This
hypothesis is guaranteed in supersymmetric models and in non-SUSY models that
obey a softly broken Peccei-Quinn symmetry.
