High HIV prevalence among men who have sex with men (MSM) and transgender women in Thailand suggest a vital need for targeted interventions. We conducted a cross-sectional survey to examine and compare sexual risk behaviors, and demographic and behavioral correlates of risk, among MSM and transgender women recruited from gay entertainment venue staff and community-based organization (CBO) participants. We used venue-based sampling across nine sites in Bangkok and Chiang Mai. Among 260 participants (57.3% gay-identified, 26.9% heterosexual/bisexual-identified, 15.8% transgender; mean age = 26.7 years), nearly one-fifth (18.5%) reported unprotected anal sex (UAS), half (50.4%) sex in exchange for money, and one-fifth (20.0%) STI diagnosis (past year). Nearly one-fourth (23.1%) reported oral erectile dysfunction medication use and nearly one-fifth (19.2%) illicit drug use (past 3 months). Overall, 43.1% indicated that healthcare providers exhibited hostility towards them. Gay entertainment venue staff were significantly more likely to self-identify as heterosexual/bisexual (versus gay or transgender female), and to have less than high school degree education, higher monthly income, to have engaged in sex in exchange for money, sex with women and unprotected vaginal sex, but were significantly less likely to have engaged in UAS than CBO participants. Targeted interventions for younger MSM and transgender women, for non gay-identified men, and strategies to address structural determinants of risk, including low education and discrimination from healthcare providers, may support HIV prevention among MSM and transgender women, and serve broader national HIV prevention efforts in Thailand.