Galactic extremely metal-poor stars are the sites where we can find the less processed material of the whole Universe. They are second generation-small mass stars but born out from gas polluted by a previous generation. Thus they preserve the chemical signature of the stars which made the early build-up of elements. In this talk, I will review the chemical abundances and chemical pattern of the small number of almost pristine stars ([Fe/H] < - 5) and the possible presence of distinct subclasses. The puzzling low Lithium abundance will be also briefly discussed.