INTRODUCTION:Gay and bisexual men (GBM) often use illicit drugs to enhance sexual pleasure, commonly referred to as 'chemsex' or 'party n play'. In particular, the use of methamphetamine and Viagra™, and other erectile dysfunction medications, both together and separately are strongly predictive of subsequent HIV infection. Truvada™, as pre-exposure prophylaxis (PrEP), virtually eliminates HIV transmission during condomless anal intercourse (CLAI). HIV-negative GBM in intensive sex partying networks may be adding PrEP to their drug regimen to actively reduce the possibility of HIV transmission during chemsex. AIM:We describe the prevalence and context of concurrent use of methamphetamine, Truvada™ (or its generic formulations), and Viagra™ or other erectile dysfunction medication (collectively, MTV). METHOD:The Following Lives Undergoing Change study is an online prospective observational study of licit and illicit drug use among Australian GBM. Between January and July 2017, 1831 GBM provided details about their use of MTV. Binary logistic multiple regression analysis were used to estimate adjusted odds ratios (aOR) and associated 95% confidence intervals (95%CI). RESULTS:Concurrent MTV use was reported by 6.0% of participants; 3.1% used methamphetamine and Viagra™ or other erectile dysfunction medication ('MV only') and 11.2% used Truvada™ as PrEP ('T only'). In multivariate analysis, compared to use of 'MV only', MTV was independently associated with CLAI with casual partners (aOR = 6.78;95%CI = 1.42-32.34) and 'fuckbuddies' (aOR = 3.47;95%CI = 1.41-8.56) in the previous six months. Compared to use of 'T only', MTV was independently associated with being older (aOR = 3.95;95%CI = 1.55-10.03) and engaging in group sex (aOR = 3.31;95%CI = 1.82-6.00). Greater social engagement with other gay men (aOR = 1.44;95%CI = 1.18-1.76) and having more sexual partners (aOR = 2.30;95%CI = 1.10-4.82) were independently associated with use of MTV compared to use of 'MV only' or 'T only'. CONCLUSION:GBM in intensive sex partying networks are increasingly adding PrEP alongside other drugs they use to enhance sexual experiences. Interventions that promote the use of PrEP during chemsex could mitigate HIV risk.