  We propose a simple supersymmetric SO(10) GUT model with only doublet Higgs
scalars. The fermion mass problem is naturally solved by a new one-loop
diagram. R-parity is conserved implying a stable LSP which can explain the dark
matter of the universe. There are two contributions to the neutrino masses, one
of which depends on the quark mass squared while the other is independent and
similar to the type II see-saw mechanism. In the latter case $b-\tau$
unification implies large neutrino mixing angles. The baryon asymmetry of the
universe is explained through leptogenesis.
