A prospective study of the serological markers of hepatitis B virus (HBV) including hepatitis B virus surface antigen (HBsAg) and hepatitis B surface antibody (anti HBs) was conducted over 5 years in Bamako. The aims of this study were to assess the prevalence of HBsAg in pregnant women and to determine the risk of HBV infection for this population. The study involved 829 pregnant women for whom blood samples were collected after the first quarter of pregnancy. HBsAg and anti HBs were detected in all cases by radioimmunoassay. The prevalence of HBsAg and anti HBs in pregnant women was respectively 15.5% and 16.9%. This prevalence of HBsAg, higher than in the general population, points to the fact that pregnant women are a high risk group for hepatitis B infection. In addition, scarification and tattooing practices increase significantly the risk of infection by hepatitis B virus (OR = 2.03; 1.07 < OR < 3.82; chi 2 = 5.62; p: 1%). Thus, we can presumably conclude that infants and new borns in such conditions are largely exposed to hepatitis B virus infection, even though hepatitis B core antibody and hepatitis B e antigen were not investigated for technical reasons. In conclusion, the authors believe that infants and new borns must be systematically immunised against hepatitis B virus infection in Bamako.