Objectives
The Thai Red Cross Anonymous Clinic in Bangkok, established in 1991, was the first centre in Asia to provide anonymous, voluntary counselling and testing for HIV infection. We present outcomes of testing for the period 1997–2004.

Methods
Newcomers to the Thai Red Cross Anonymous Clinic were invited to complete a brief questionnaire concerning HIV risk behaviour and personal characteristics. The questionnaire was linked by code numbers to the HIV test result. Information obtained from the pretest questionnaire and HIV antibody test results from January 1997 to December 2004 were analysed. Data are presented as means [with standard deviation (SD)], medians [with interquartile range (IQR)] or percentages. Multivariate analysis using logistic regression was performed to identify factors predicting a positive HIV test result.

Results
Over the 8-year study period, 65 807 new clients attended the clinic. Two-thirds were male and the mean age was 31.7 years (SD 9 years), and more than half were single. The proportion of high-school graduates was 43%, and 36% earned more than 10 000 Baht a month (40 Baht:$US1). Of 54 578 new clients who had an HIV test during the study period, 17.5% had a positive test result. In multivariate analysis, predictive factors for HIV positivity included female gender, age group 25–34 years, widowed status (women), residence outside Bangkok, birthplace in a northern province, no formal schooling, farmer as profession, and salary less than 5000 Baht a month (the current legal minimum daily wage set by the Thai Ministry of Labor is 181 Baht).

Conclusions
With nearly 7000 clients newly tested for HIV infection each year, the Anonymous Clinic in Bangkok has provided a unique epidemiological window into the patterns of HIV infection in the Thai capital.