The BCG vaccine is the most given throughout the world, and the immunization coverage is the highest: 72 % in 1989 for children under one year of age. Following doubts which appeared in 1980 concerning its efficacy, many epidemiological studies confirmed the protective potency of this immunization against the severe forms of tuberculosis in children. Recent problems of tolerance arised but are now resolved by the adaptation of the vaccine concentration to the routine immunization of newborns. The world wide epidemic of AIDS and the concomitant recent increase in tuberculosis cases encourage to sustain the effort of immunization of infants. However, questions of theoretical interest have been shelved on this subject: is it reasonable to immunize HIV positive children in absence of clinical signs in countries with high prevalence? Is the vaccine effective in these special cases? Is it safe? In any case, it is the only effective and cheap way, and probably with no risk, of preventing child tuberculosis meningitis in endemic disease countries.