The clinical course and immunodiagnosis of hepatitis B infection is discussed. Immunization is necessary to prevent the clinical disease, the development of carriers, and the transmission of the hepatitis B virus to susceptible persons. Host factors that can curtail the immune response include increasing age, obesity, smoking cigarettes, and having a medical condition that compromises the immune system. Increasing the dose of vaccine, administering the inoculations intramuscularly, and giving the vaccine more frequently can enhance the immune response. The duration of immunity following vaccination has not yet been defined, but booster dose guidelines for selected groups are provided. Finally, recommendations for developing and implementing hepatitis B immunization protocols are presented.