  We investigate the prospects of an extra global symmetry, added to the
Standard Model in the context of baryogenesis. The $PQ$ symmetry is studied as
an example. We show that the hadronic axion provides a protection of the
B-asymmetry even if $B-L$=0 and that there are no limits on the neutrino
masses. It is also shown that there is a crucial difference between the two
possible invisible axion models. A connection between the baryon asymmetry and
dark matter is also pointed out.
