HIV prevalence and associated factors were examined among male sex workers (MSWs, N = 414) in Bangkok, Thailand. Cross-sectional venue-day-time sampling was used to collect data in entertainment and street venues. Chi-square and logistic regression were used to identify HIV risk factors. HIV prevalence was 18.8% overall, but differences were found between MSW recruited in entertainment and street venues. Significant relationships were found between several demographic, behavioral, exposure to HIV prevention, and other characteristics, and recruitment location. In multivariate analyses, being sexually attracted to men was significantly associated with HIV infection among both groups of sex workers. In addition, among street-based sex workers, not having had sex with a woman in the past 3 months, having ever had a sexually transmitted disease symptom, and not having a friend to talk to about personal problems were significantly associated with HIV infection.