  We study, in the framework of the Standard Model, the propagation of (pure)
Majorana neutrinos in a typical stellar medium and show that Majorana neutrino
matter oscillations are completely indistinguishable from Dirac ones, even if
in the case of no family mixing Majorana neutrinos can be distinguished from
Dirac ones in the non-relativistic limit. Moreover, if CP violation is present,
an effective phase arises in the effective mixing matrix but, due to a symmetry
of the Majorana fields, this cannot be univocally determined
