Pre-exposure prophylaxis (PrEP) can reduce HIV transmission risk for many gay, bisexual and other men who have sex with men. However, bacterial STI (BSTI) associated with decreasing condom use among HIV PrEP users is a growing concern. Determining the characteristics of current PrEP users at highest BSTI risk fills a critical gap in the literature. Gay and bisexual men (GBM) in New York City on HIV PrEP for 6 or more months (n=65) were asked about chlamydia, gonorrhoea and syphilis diagnoses in the past 6 months. By design, half (51%) of the sample were club drug users. We examined the associations of length of time on PrEP, type of PrEP care provider, PrEP adherence, number of sexual partners, number of condomless anal sex acts and club drug use on self-reported BSTI using multivariable, binary logistic regressions, adjusting for age, race/ethnicity, education and income. Twenty-six per cent of GBM on HIV PrEP reported a diagnosis of BSTI in the past 6 months. Men who reported club drug use (adjusted OR (AOR)=6.60, p<0.05) and more frequent condomless anal sex in the past 30 days (AOR=1.13, p<0.05) had higher odds of reporting a BSTI. No other variables were significantly associated with self-reported BSTI in the multivariable models. Club drug users could be at a unique BSTI risk, perhaps because of higher risk sexual networks. Findings should be considered preliminary, but suggest the importance of ongoing BSTI screening and risk-reduction counselling for GBM on HIV PrEP. © Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.