The lack of expensive equipment and well-trained laboratory technicians in developing countries makes it difficult to use standard methods (2 EIA confirmed by western blotting) to diagnose HIV infection. This led the WHO to develop simplified algorithms based on sequential screening tests, with no confirmation by immunoblotting. These algorithms were tested in the normal diagnosis conditions of a medical unit in Maputo, Mozambique. We tested 402 sera, collected with the consent of the patients concerned. The sera were first tested for HIV according to French regulations (2 EIA with western blot if at least one EIA was positive). This strategy identified 53 sera as positive for HIV1 and 1 serum as positive for HIV2. We then tested who algorithms, one for a predicted rate of prevalence < 10% and the other for a predicted rate of prevalence > 10%. Neither algorithm performed adequately for diagnostic purposes. Further evaluation with a panel of local sera is required to select the most suitable algorithm in terms of specificity and sensitivity, and algorithms should be throughly tested before inclusion in national AIDS control strategies.