  In this paper we discuss some results concerning the abundance discrepancy
problem in the context of H II regions. We discuss the behavior of the
abundance discrepancy factor (ADF) for different objects and ions. There are
evidences that stellar abundances seem to agree better with the nebular ones
derived from recombination lines in high-metallicity environments and from
collisionally excited lines in the low-metallicity regime. Recent data point
out that the ADF seems to be correlated with the metallicity and the electron
temperature of the objects. These results open new ways for investigating the
origin of the abundance discrepancy problem in H II regions and in ionized
nebulae in general.
