HIV prevalence and associated risk behaviors were examined among Thai bisexually active men (MSMW, n = 450) and men who have sex with men only (MSM-only, n = 1,125). Cross sectional venue-day-time sampling was used to collect data. Chi-square and logistic regression were used to identify HIV risk factors. HIV prevalence was 8.2% among MSMW and 21.2% among MSM-only. Consistent condom use with male partners was higher among MSMW (77.6%) than MSM-only (62.9%), and lower with female partners (44.4%). Lack of family confidant, migration, concern about acquiring HIV infection, and self-reported STD were associated with HIV prevalence among MSMW. Older age, lower educational level, residing in Bangkok or Chiang Mai, living away from family, recruitment from a sauna, increased frequency of visiting the surveyed venue, practicing receptive or both receptive and insertive anal intercourse, inconsistent condom use with male paying partners, and a history of drug use were associated with HIV prevalence in MSM-only.