The search for the most galactic metal-poor stars began soon after the publication of the fundamental paper of Burbidge et al. (1957): the elements are synthesised little by little in the stars, and thus the most metal-poor galactic stars are (at least in a first approximation) the oldest ones. The abundances of the elements tell us the story of the evolution of our Galaxy. I will try to recall the contribution of the La Silla instruments to the detection and the study of the primitive metal-poor stars, and I will rapidly review what we know today about the early phases of the Galactic evolution.