Of 5180 consecutive outpatients diagnosed with tuberculosis in Abidjan, Côte d'Ivoire (West Africa), between July 1989 and December 1990, 289 (6%) were children aged less than 15 years. The overall prevalence of human immunodeficiency virus (HIV) 1 and/or HIV-2 infection in children with tuberculosis was 11.8% (HIV-1, 10.0%; HIV-2, 0.7%; reactivity to both viruses, 1%). The highest overall age-specific prevalence was in children aged 1-4 years (23.4%), significantly higher than the rate in attenders at a well child clinic (0.5%) (odds ratio 58.2). Of children with tuberculosis, 26% had sputum smear-positive disease (HIV seroprevalence 2.7%), 20% extrapulmonary disease (HIV seroprevalence 5.2%), and 54% were categorized as having 'clinical tuberculosis' (HIV seroprevalence 18.6%) based on clinical signs and chest X-ray abnormalities with negative sputum smears. Clinical tuberculosis was most frequent in seropositive children, irrespective of age, and in younger seronegative children. Extrapulmonary tuberculosis was equally distributed across age groups, and pulmonary tuberculosis was concentrated in older, seronegative children. HIV-positivity was significantly associated with other features related to the acquired immune deficiency syndrome such as wasting, chronic diarrhoea, oral candidiasis, and negative tuberculin skin tests. Tuberculosis seems to be associated with HIV infection in children in sub-Saharan Africa, but better diagnostic techniques for paediatric tuberculosis are urgently needed.