72% of 1169 gay men surveyed at 3 different circuit parties reported using ecstasy at least once in the last 12 months (app. 842 men). Respondents represented app. 0.02% of potential respondents (estimated combined attendance = 50,000). Other commonly used drugs were alcohol (79%) and ketamine (60%). Other drugs, including cannabis, GHB and "poppers," were used as well. Frequent, but not occasional, use of ecstasy, ketamine and "poppers" at circuit parties was associated with unsafe sex (defined specifically as unprotected anal sex). Stated reasons for attending circuit parties, such as "to look and feel good" or "to have sex," were also associated with unsafe sex. Use of poppers in previous 12 months was associated with unsafe sex in general. Reported rates of unsafe sex were low (15%). The findings in this paper suggest that frequent drug use, including use of ecstasy, may be associated with unsafe sexual practices in gay men attending circuit parties. The association is explainable both through drug effects (reduced anxiety, impaired judgment) and through individual differences in risk-taking, wherein both drug use and sexual behavior serve as indicators of risk-taking.