Numerous studies have demonstrated that men who have sex with men (MSM) experience disproportionate levels of ill-health compared to the general population, and are one of the highest risk groups for HIV in every part of the world.MSM frequently face significant stigma and discrimination from their families, communities and, in some countries, are the subject of systemic repression and persecution. Often this repression and stigmatisation can make accessing appropriate health services, where they exist, problematic.A significant concern among health professionals and advocates who work to improve the health and well-being of MSM relates to the prevalence of drug use within the population, its uses and its associated harms. The chapter begins with an overview of the range of drugs taken by MSM, followed by a description of prevalence across the world (where such data exist) and a discussion of data quality. It then assesses the reasons for drug use by MSM and the harms that may be associated with such use. The final section highlights interventions to help reduce the harms associated with drug use among MSM.