A survey of persistence of anti-HBs after hepatitis B vaccination has shown that five years after vaccination on a sample of 152 persons, or 82.53%, stands at >10 IU/I. Long term immunogenicity of vaccinated children remained at 88.89%, health workers 79.41% and drug addicts 64.28%. The results of these studies in Bosnia and Herzegovina show the high level of protection hepatitis B vaccine against HBV infection. Vaccination against viral hepatitis B results in immunologic memory response among the vaccinated, and even after a decrease of anti-HB level following the third vaccine dose inoculation, a booster dose is not needed. Immunity remains steady and a booster dose is not recommended.