We report the results of a study held between 1986 and 1988 on a population constituted by 493 subjects (425 of Mozambican nationality) all living in the camp organized for the building of the dam in Corumana (Sabiè district, Maputo). We found five subjects, all of them from Mozambique, seropositive for HIV-1 antibodies (ELISA and WB) with a prevalence of 1.2%. Four of the positive samples came from female subjects (1.7% of 239 females tested); one positive sample came from a male subject (0.5% of 186 tested).