This is a prospective study conducted as part of a voluntary testing for HBV, HCV and HIV. The aim of the study is to determine the seroprevalence of HBs Ag and anti-HCV antibodies among HIV infected people and a control group of HIV negative people. HIV prevalence among newly diagnosed volunteers is 9.1%. The overall seroprevalence of HBs Ag and anti-HCV antibodies is respectively 13.5% and 2.0%. The seroprevalence of HBs Ag and anti-HCVantibodies in the control group (HIV-negative) is respectively 12.2% and 2%. The seroprevalence of HBs Ag and anti-HCV antibodies among HIV infected people (old and new) is respectively 16.1% and 1%.This study, the first one conducted in Chad, has allowed us to know the seroprevalence of HBs Ag and anti-HCV antibodies among HIV infected people.