ObjectivesTo describe the AIDS/sexually transmitted diseases (STD) knowledge and risk behaviors, and to determine factors related to condom use among male commercial sex workers (CSW) and male tourist clients in Bali, Indonesia.DesignIndividual survey interviews were conducted with a sample of 80 male CSW and 100 tourist clients in the Kuta area of Bali.MethodsSurvey interviews included detailed questions on AIDS/STD knowledge, sexual behavior, and psychosocial measures related to risk taking.ResultsMost of the male CSW had heard about AIDS and other STD, although some misconceptions about transmission and risks of different sexual practices remained. Both oral and anal intercourse with tourists were common and condom use was far from consistent. Factors related to condom use for anal intercourse with tourist clients were condom beliefs, self efficacy, susceptibility to STD infection, and STD knowledge. Tourist clients were mainly from Australia and Europe and many had paid for sex in other parts of Indonesia as well as in high prevalence countries. Knowledge of AIDS/STD was very good among the tourists and previous experience with STD was common. Factors related to condom use with male CSW were condom beliefs and self efficacy.ConclusionThere is a very active and mobile group of male CSW and tourist clients present in Bali. Interventions with these men are needed due to the low level of knowledge about AIDS among CSW, their experience with STD and STD symptoms, and their level of risky sexual behavior.