  We propose an SO(10) grand unified theory which has the simplest Higgs
structure discussed so far in the literature. We include only two Higgs
scalars, a 210-plet and a 16-plet. In addition to the regular fermions we
include one singlet, whose mass term breaks chiral symmetry, so that fermions
can get masses. All fermions acquire see-saw masses, since there are no Higgs
bi-doublets. Required neutrino masses with large mixing as well as leptogenesis
are possible in this model.
