AbstractHepatitis B virus (HBV) infection and related diseases represent some of the major public health problems in Senegal. The prevalence of hepatitis B surface antigen (HBsAg) in infants increased steadily during their first years of life. HBsAg prevalence was 6% at 6 months of age and 13% at 2 years. HBV infection was detected in 30% at 2 years of age and in more than 90% of the population after the age of 10. Hepatitis B e antigen was detected in only 13–19% of HBsAg‐positive adults.As a consequence of this high frequency of HBV infection occurring early in life, a high frequency of hepatocellular carcinoma is observed in Senegal, with only two‐thirds of them being HBsAg carriers. However, the HBV genome was detected in 58% of HBsAg‐negative patients suffering from liver cirrhosis or primary liver cancer confirming the aetiological link between HBV and primary hepatic carcinoma in HBsAg‐negative patients. On the other hand, confirmed HCV infection has been detected in only 7% of the HBsAg‐negative liver cancer cases.More than 95% of the vaccinated infants had protective antibodies to HBsAg after a primary set of vaccine doses; this proportion decreased to 80% 6 years later and to 73% 10–12 years later. HBsAg was detected in 25% of infants from the control group and in 2.1% of immunized infants corresponding to an efficacy of more than 90%. No difference was observed between infants who received a booster dose at school age and those who did not. On the other hand, the results show that hepatitis B vaccine may be introduced into the existing recommended Expanded Programme on Immunization schedules without reducing the immune response to any of the currently recommended antigens nor increasing the frequency of untoward reactions.