The seroprevalence of human herpesvirus 8 (HHV-8) was studied in 326 human immunodeficiency virus (HIV)-positive and -negative persons from Honduras; women constituted 77% (n = 251) of the subjects. Sera were tested for lytic HHV-8 antibodies by an IFA, and positive samples were confirmed by a radioimmunoprecipitation assay. Of the 326 persons tested, 58 (17.8%) had HHV-8 antibodies. Among the HIV-infected women, 22.7% were seropositive; 11.3% of the HIV-negative women were seropositive. HHV-8 seroprevalence was almost four times higher in HIV-positive female commercial sex workers (36%) than in HIV-negative female non-commercial sex workers (9.9%; odds ratio = 3.8, 95% confidence interval = 1.1-13; P = 0.01), suggesting that commercial sex work is a risk factor for HHV-8 infection. In the men studied, the overall HHV-8 seroprevalence was 22.6%, with a seropositivity rate of 28% for HIV-positive men compared with 12% for HIV-negative men.