HIV-associated infections in sub-Saharan Africa differ markedly in their incidence from those in industrialized countries. Tuberculosis is the commonest cause of morbidity and mortality. Enteric pathogens such as microsporidiosis commonly cause disease as access to safe water is limited. Pneumocystis carinii pneumonia, which is the commonest opportunistic infection in industrialized countries, is uncommon in adults with HIV infection. This remains unexplained because P. carinii pneumonia is common in Black African HIV-infected children. Cytomegalovirus and Mycobacterium avium complex, which only occur in severely immune-suppressed individuals, are seldom found. One reason may be that survival after conversion to AIDS is relatively short in Africa. Patients often die before they develop severe immune suppression. Recently, prophylactic cotrimoxazole treatment was shown to be effective in symptomatic HIV-infected adults in Africa. Tuberculosis preventive therapy is also effective in Africa, at least in the medium term. It is hoped that these two affordable interventions will become available to large numbers of patients identified in voluntary counselling and testing centres.