Hepatitis B is the most important infectious occupational disease for health care workers. The high risk of being infected is the consequence of the prevalence of virus carriers in the assisted population, the high frequency of exposure to blood and other body fluids and the high contagiousness of hepatitis B virus (HBV). Vaccination is able to prevent the most threatening consequences of the infection (acute disease and chronic carriage) in responders, even after loss of detectable antibodies. Non-responders to the primary series may benefit from administration of up to three more doses of vaccine (40-70% of initial non-responders show seroconversion to the new series). However, newly developed vaccines that seem more immunogenic are presently under evaluation and should further decrease the number of non-immune workers in the near future. In the mean time, coverage with standard vaccines should be improved also by supplying complete information on the risks of hepatitis B and on the safety and efficacy of active immunisation.