  The observed phenomenon of neutrino oscillations is interpreted as the proof
that neutrinos must have mass. As this is true for the neutrinos in the mass
basis, the mass matrix in the flavor (weak) basis may still contain zeros. This
can happen if the CP violating phases, usually neglected, come into play and
result in suppression of processes which half-life depends on the masses of
$\nu_e$, $\nu_\mu$, or $\nu_\tau$. In the present paper we investigate the
possibility of such suppression of the neutrinoless double beta decay
($0\nu2\beta$).
