  A period-metallicity relation for oxygen-rich Miras derived from globular
clusters is applied to similar variables in the galactic Bulge. The metallicity
distribution in the Bulge thus obtained is in good agreement with that derived
from K giants. This suggests that the periods of Miras are useful indicators of
metallicity distributions, at least in old systems such as galactic bulges. For
systems such as the LMC the situation is not yet clear.
