The authors tried to find out the incidence of HIV positive women in 634 deliveries in the two large maternity units in Libreville. The prevalence was 1.26% which is a net rise compared with previous figures in the same city, but remains lower than figures for other large cities in Central Africa. Transmission is mainly by the sexual route and in particular by the heterosexual route and the virus particularly affects young women at their most fertile which makes the epidemic all the more serious because of congenital aids.