Several studies have recognised that men who have sex with men (MSM) suffer disproportionately of substance use disorders and their negative health outcomes compared to the general population. Yet, public health initiatives concerning (MSM) have thus been monopolised by HIV and AIDS prevention. The construct of "Gay and HIV" still stands with a firm foot in healthcare today: it can be regarded as a socio-political and economic framework that discriminates and leads to disparate health outcomes for MSM. In Geneva, to date, no recent studies concerning substance use and its associated health risks exist. The aim of this study is to determine the prevalence of substance use and the correlates with social, financial and health outcomes, in a sample of MSM consulting Checkpoint Geneva for HIV & STI counselling and testing.