A population-based serosurvey of human immunodeficiency virus in Belle Glade, FL, enabled evaluation of risk factors for hepatitis B virus (HBV) infection in this racially mixed community. Serum samples from 725 adults and 130 children were tested for markers of HBV infection, and histories of exposure to HBV were obtained by interview. The overall prevalence of past or present HBV infection was 26%; prevalence was 9% among whites, 5% among Hispanics, 30% among blacks, and 57% among Haitians. Prevalence of HBV infection was 3% in children aged 2-10 years and increased to 31% in adults greater than 17 years. Of adults seropositive for HBV, only 5% had homosexual partners or used parenteral drugs, but 47% had a positive serologic test for syphilis. Factors associated with HBV infection in adults were positive serologic test for syphilis (odd ratio [OR] = 3.1; 95% confidence limits [CL] = 2.0, 4.8), and having had two or more lifetime heterosexual partners (OR = 3.2; 95% CL = 1.6, 6.4). In this community, HBV infection was transmitted predominantly by heterosexual contact.