Hepatitis B is highly endemic in Senegal. The prevalence of hepatitis B antigens in the population was estimated to be 10 to 12% in 1982. According to the WHO recommendations, a hepatitis B vaccination program (HBV) was launched in 10 medical centers in the Kolda medical region to assess the feasibility of including HBV in the EPI. The epidemiological impact of HBV was also investigated by comparison of the vaccinated zone (VZ) to a control non vaccinated zone (NVZ). HBV coverage had a pattern similar to that of DPT-IPV, but at a lower level: the overall coverage with HBV was only 37.5%, and the drop out rate for HBV1-3 was only 34.4%. In addition, the coverage of the under one year age group was insufficient: 45% for HBV3 as compared to 78% for DPT3 (p < 0.0001). Routine vaccination records in the medical centers in the VZ were consistent with the findings of cluster surveys. Hepatitis B markers were less prevalent among vaccinated that non vaccinated children (8 versus 18.5%, p < 0.001). HB antigenemia was significantly less frequent in the VZ than the NVZ (3.9 versus 10.9, p < 0.0001), and the difference was even larger for all hepatitis markers (7.4 versus 23.7%, p < 0.0001). This study therefore suggests that the inclusion of HBV in the EPI should be continued and strengthened in less accessible regions by an adapted social mobilization program. HBV could then be extended to the whole medical district of Kolda in association with regular epidemiological and serological surveillance.