BACKGROUND:Reliably measuring drug use by gay, bisexual and other men who have sex with men (GBM) in the context of sex can inform sexual health service responses. We report changing drug use patterns among GBM testing for HIV at a community-based service in Melbourne in response to behavioural survey modifications. METHODS:Surveys were completed by GBM prior to all HIV tests. Survey one asked about use of "party drugs for the purpose of sex" and survey two asked about specific drug use (alcohol, amyl nitrate, methamphetamine, cocaine, ecstasy, GHB, Viagra®/Cialis®) before or during sex. Differences in drug use prevalence and demographic and sexual risk correlates are reported. RESULTS:Reported drug use increased from 16.9% in survey one to 54.0% in survey two. Among GBM completing both surveys, 45% who reported no drug use in survey one reported drug use in survey two. Drug use was associated with high HIV risk behaviours across both surveys. CONCLUSION:Survey modification improved ascertainment of drug use in the context of sex among GBM. Continued monitoring of drug use in this setting will improve our understanding the relationship between use of specific drugs and sexual health and help inform client focused health promotion.