During the study, there were 863 admissions and 109 discharges. The treatment program was divided into three phases related to the progress of rehabilitation with methadone maintenance. During phase one, a 6-week period of hospitalization on an open medical ward, the patients are brought to a blockading level of methadone. Phase two begins with a patient's discharge to the outpatient clinic and continues for at least a year. Phase three is reached when the subject has become a stable and socially productive member of the community and can be treated as an ordinary medical patient. Patients were addicts with a history of at least 4 years of main-line heroin use and repeated failures of withdrawal treatment who were admitted to the methadone maintenance program in order that they applied, subject to the following conditions: age 20 to 40, no legal compulsion for treatment, no major medical complication, and a resident of New York City. Prior to treatment, 91 percent of the patients had been in jail, and all had been continuously involved in criminal activities. Since entering the treatment program, 88 percent of the patients show arrest-free records. The majority of patients have stopped heroin use completely after starting methadone treatment. This has been verified by repeated analyses of urine. The greatest surprise has been the high rate of social productivity as defined by stable employment and responsible behavior, which indicates that when pathological drug hunger is relieved, positive behavior can emerge. Tabular and graphic data are provided, along with six references.