To many observers from outside the United Kingdom (U.K.), the British System is synonymous with heroin maintenance, with doctors supplying drugs on demand to addicts. To some it has been viewed as an approach of extreme folly; to others it is an effective policy of supreme pragmatism. To those who know and work within it, the British System is somewhat more complex. Indeed, the extent to which a clearly defined system can be identified has been the focus of debate. Here, we will demonstrate that a particular set of factors have combined in the U.K. to create an evolving system of care for drug takers, which has been responsive both to the changing drug scene and to the individual needs of the drug taker. This review will identify the key characteristics of the British System. Important historical milestones...