  We present new evolutionary models for zero-metallicity stars, covering a
large range of initial masses (from 0.8 to 100 M_sun). Models are computed with
overshooting from stellar cores and convective envelopes, and assuming
mass-loss from the most massive stars. We discuss the main evolutionary
features of these stars, and provide estimates of the amount of
newly-synthesized elements dredged-up to the stellar surface, and possibly lost
by stellar winds from the most massive stars. Full details of these models will
be given in Marigo et al. (2000, in preparation).
