  The first massive stars triggered the onset of chemical evolution by
releasing the first metals (elements heavier than helium) in the Universe. The
nature of these stars and how the early chemical enrichment took place is still
largely unknown. Rotational-induced mixing in the stellar interior can impact
the nucleosynthesis during the stellar life of massive stars and lead to
stellar ejecta having various chemical compositions. We present low and
zero-metallicity 20, 25 and 40 $M_{\odot}$ stellar models with various initial
rotation rates and assumptions for the nuclear reactions rates. With increasing
initial rotation, the yields of light (from $\sim$ C to Al) and trans-iron
elements are boosted. The trans-iron elements (especially elements heavier than
Ba) are significantly affected by the nuclear reaction uncertainties. The
chemical composition of the observed CEMP (carbon-enhanced metal-poor) stars
CS29528-028 and HE0336+0113 are consistent with the chemical composition of the
material ejected by a fast rotating 40~$M_{\odot}$ model.
