During the years 1992-1994, we tested 948 individuals from different population groups for HIV-1 and HIV-2 infections by ELISA and WB and for HCV infection by ELISA. Repeated ELISA reactivity for HIV was found in 2.12% of blood donors, 2.95% of fire brigade personnel and 1.61% of prisoners. Western blotting studies, however, showed that these samples were non-reactive or indeterminate to either HIV-1 or HIV-2. In contrast, anti-HCV antibodies were detected in 39% of fire brigade personnel, 31.4% of prisoners and 20.8% of blood donors. The analysis of risk factors for acquiring HCV infection showed a strong association between a past history of parenteral therapy for schistosomiasis and anti-HCV seropositivity (p < 0.0001). The implementation of preventive strategies is at the moment the mandatory choice to stop a further spread of the HCV infection. Meanwhile the same preventive measures could avoid spreading of the HIV disease.