  By modeling the rich emission line spectra of a sample of high redshift
(HzRG, z\sim 2.5) radio galaxies we find that solar and supersolar
metallicities are common in the extended gas of these objects. Our models and
the comparison with high redshift quasars suggest that HzRG at z\sim 2.5 are
associated with intense star formation activity. This is consistent with
chemical evolution models for giant ellipticals and it supports the idea that
distant powerful radio galaxies are progenitors of giant ellipticals. We might
be witnessing different evolutive status in different objects.
