This paper presents data from the first British prospective study to investigate relapse among opiate addicts after treatment. Eighty subjects were followed up over the six-month period immediately after discharge from treatment and were interviewed on several occasions. Large numbers of subjects used opiates within a very short time after discharge; 71% used them within the first six weeks. However, this first lapse to opiate use did not herald a full-blown relapse to dependent use. There was a gradual increase in the number of abstinent subjects, with 45% abstinent and living in the community at the six-month point. The practical and theoretical implications may be regarded as broadly encouraging.