Factors associated with awareness and acceptance of hepatitis B vaccine were identified among 150 homosexual male clients of a Boston community health center. Five percent of the subjects were unaware of hepatitis B and 25 percent had a history of hepatitis. Among the remaining 106 men, 68 percent were aware of the vaccine, and 25 percent of these had been vaccinated. Awareness of vaccine was associated with education beyond the baccalaureate level. Factors associated with vaccination included at least one prior visit to the health center, having health insurance, and extent of knowledge of the effects of hepatitis B. Among those not vaccinated, 68 percent would like to be but were deterred by the perceived high cost of the vaccine. The predominant reason given by the 31 percent who have decided not to be vaccinated was the perception that they were not at risk because of monogamous sexual relationships, or "safer" sexual practices. Strategies for maximizing vaccine use among homosexually active men should focus on increasing both awareness of the vaccine and appropriate perceptions of risk.