Résumé : From December 1982 to June 1985, we diagnosed LAV/HTLV-III infection in 16 children of African origin living in Belgium or referred to one of the hospitals participating in this study. Diagnosis was proven in seven of them by isolation of virus of the LAV/HTLV-III group. In the nine others, LAV/HTLV-III infection was highly probable because of the presence of antibodies against the virus (seven subjects) or clinical and immunological evidence of immune deficiency associated with a parental history of LAV/HTLV-III infection (two subjects). Five of these children had a severe illness starting in the first months of life (range 20 days-4 months) and died within 4 months (range 19 days-10 months). Eight children presented later in life (mean age 35 months, range 2-66 months) with a milder and more chronic disease characterized by the presence of generalized lymphadenopathy (6/8), hepatomegaly (5/8), splenomegaly (5/8), interstitial pulmonary infiltration (4/8), parotid swelling (3/8), CSF lymphocytosis (3/5), diarrhoea without pathogen isolated (1/8) and fever (1/8). At least one of the parents of each child was of African origin. At the time of birth of their child two mothers and one father had an AIDS-related complex. After a mean period of 34 months (range 3-87 months) five fathers and six mothers had a symptomatic LAV/HTLV-III infection (AIDS or AIDS-related complex). © 1986 Springer-Verlag.