In this paper we present a study of chemical abundances in six star-forming regions .
Stellar parameters and metallicities are derived using high-resolution , high S/N spectra of weak-line T-Tauri stars in each region .
The results show that nearby star-forming regions have a very small abundance dispersion ( only 0.033 dex in [ Fe/H ] ) .
The average metallicity found is slightly below that of the Sun , although compatible with solar once the errors are taken into account .
The derived abundances for Si and Ni show that the observed stars have the abundances typical of Galactic thin disk stars of the same metallicity .
The impact of these observations is briefly discussed in the context of the Galactic chemical evolution , local inter-stellar medium abundances , and in the origin of metal-rich stars in the solar neighbourhood ( namely , stars more likely to harbour planets ) .
The implication for future planet-search programmes around very young , nearby stars is also discussed .