This paper reports the success of outreach efforts to immunize adults at high risk of acquiring hepatitis B virus (HBV) infection. Local health department testers recruited clients when they sought anonymous HIV testing. Interested clients were serologically tested for HBV infection. Susceptibles were offered a free hepatitis B vaccine. Of 189 clients who were tested, 161 (86%) were susceptible to HBV infection and 140 (74%) were men who have sex with men (MSM). Of the susceptibles, 82 (51%) started the hepatitis B vaccine series. Sixty-five (80%) received three doses of hepatitis B vaccine and an additional 10 (12%) received two doses. Completing the hepatitis B vaccine series was associated with being a MSM (odds ratio [OR] 8.8, confidence interval [CI] 1.5-56.0) and with not being an injection drug user (IDU) (OR 0.2, CI 0.02-1.0). One way to provide hepatitis B vaccine to MSM is to attach an immunization program to a successful anonymous HIV testing program. The feasibility of implementing such programs would increase if public vaccine policymakers made more federally purchased hepatitis B vaccine available for adults.