Prisoners have been thought to be at high risk of contracting hepatitis B. Prevalence studies throughout the world show a similar hepatitis B marker rate of 28 to 51%. Seroconversion studies have shown a 0.8 to 1.4% incidence in male prisoners. These results are far less than the predicted 5 to 10% annual attack rate for a similar non-incarcerated population. Cost considerations prevent universal vaccination of prisoners, but IV drug abusers and female prisoners seem to be at especially high risk and should be targeted for immunization now. Prisoners who are chronic carriers of HBsAg and who are also "e" antigen positive or delta antibody positive should be segregated.