  Detection and analysis of Wolf-Rayet (WR) star populations in young
starbursts is a powerful tool to reveal the properties of the star-forming
events. We present new high S/N optical spectra of a sample of well-known WR
galaxies, in which we detected for the first time the spectral signature of WC
stars. The detailed comparison of WN and WC star populations derived in these
galaxies, with the most recent model predictions, allows to put tight
constraints on starburst parameters, such as the age and duration of the burts,
and the IMF.
