The aim of this study is evaluation long term protection of HBV vaccine in adult. Hepatitis B vaccine is one of the safest vaccines available in the world. This study is a descriptive cross-sectional that conducted in five hundred five settled person of military in capital city of Iran in 2006. All subjects that have past history of HBV vaccination recruited to study. Demography data and date of recent HBV vaccine and anti HBS antibody and HBs Ag and HBc Ab were record. Data was analyzed with SPSS 13 program and Chi-square and t-test were used. All subjects were man with mean age 33.9±8.9 SD years old. Education level in 81.4% was in diploma degree and above. Anti HbsAb was positive in 498 (98.6%) of staff and 2(0.04%) had HbsAg and HbC Ab positive. This study showed that three dose of vaccine protective until ten years after HBV vaccination. Therefore, Booster HBV vaccine will not require at least until ten years after complete vaccine program.