HIV infection of the newborn is now known to result mostly from mother-to-foetus transmission. The risk of transmission is at least 40 p. 100. However, the circumstances of passage are little known, and there is no maternal virological parameter capable of evaluating individual risks. The disease is more severe in children than in adults. Rare are the children who remain asymptomatic for more than 15 months; one out of three of them develop severe acquired immunodeficiency syndrome and die within the first 2 or 3 years of life. A specific encephalopathy is observed in about 30 p. 100 of the infected children. Kaposi's sarcoma is exceptional. Since there is no contagion between children, those who are in fairly good clinical condition should have a family and school life as normal as possible.