Drug addiction is a serious social problem, placing a burden on health and social services as well as the criminal justice system. Although only a minority of addicts use heroin, it is associated with some of the most significant health and social costs of drug misuse. Effective treatments of drug addiction have proved elusive. One major reason for this is that although many addicts can overcome their addiction for a short period of time, their craving for opiates continues and leads to most relapsing in the long term. This research will investigate the brain mechanisms of craving and cognition in recently abstinent opiate addicts. It will also determine whether differences in brain function can predict whether individual addicts will relapse after discharge from a treatment programme. If key differences can be identified, this could provide the basis for the development of more effective treatments. We will provide information about our findings to the media, to users groups and on our website.