A cross-sectional study was conducted on 200 commercial sex workers (CSWs) from two brothel communities in Central Java, Indonesia, to determine the seroprevalence of syphilis and HIV and characterize associated knowledge, beliefs, and risk-taking behaviors. A questionnaire was administered and blood drawn for HIV and syphilis serologies. Focus groups with a total of 20 women were also conducted at both communities to supplement survey data. The mean CSW age was 27.3 years; mean number of clients seen per day was 2.27. The prevalence of syphilis and HIV were 7.5% and 0.5%, respectively. Thirty percent said they and their partners never used condoms during sex, and only 3.0% said they always used condoms. The most common client groups were truck drivers and sailors. While Central Java appears to remain in a pre-epidemic state, there is enormous potential for a significant increase in HIV and STD transmission.