The United Nations Office on Drugs and Crime (UNODC) estimates that there are presently between 15.5 and 21.1 million opiate users in the world, the majority of whom are heroin users.1 There has been a growing awareness of the importance of treatment for this population in recent decades, with Opiate Substitution Therapy (OST) prominent amongst the range of treatment modalities. While methadone remains the most widely used substitute, clinicians and researchers recognise that there is a significant number of users for whom methadone has proved ineffective. This recognition has driven an expansion in the range of substitution modalities, and, in some parts of the world, clinicians have employed heroin (or, more precisely, diacetylmorphine or diamorphine, its licit, unadulterated pharmaceutical form) in the treatment of opiate addiction.

This briefing paper explores the question of Heroin Assisted Treatment (HAT), examines the growing body of evidence emerging from its clinical use in addiction therapies, and makes recommendations for policy makers.