  We present observational estimates of DV(Bump-HB) in a sample of 28 Galactic
Globular Clusters (GGCs) observed by HST. The photometric accuracy and the
sizable number of stars measured in each cluster allowed us to single out the
RGB Bump both in metal-poor and in metal-rich GGCs. Empirical values are
compared with homogeneous theoretical predictions which account for both H and
He burning phases over a wide range of metal abundances (0.0001 < Z < 0.02). We
found that, within current observational uncertainties on both iron and
$\alpha$-element abundances, theory and observations are in very good
agreement, provided that the metallicity scale by Carretta & Gratton (1997) as
extended by Cohen et al. (1999) is adopted. Interesting enough, we also found
that both theoretical and observed values show a change in the slope of the
DV(Bump-HB)-[M/H] relation toward higher metal contents.
