  By combining the inputs from the neutrinoless double beta decay and the fits
of cosmological models of dark matter with solar and atmospheric neutrino data,
we obtain constraints on two of the mixing angles of Majorana neutrinos, which
become stronger when coupled with the reactor neutrino data. These constraints
are strong enough to rule out Majorana neutrinos if the small angle solution of
solar neutrino puzzle is borne out.
