After an average follow-up period of 7.6 years, researchers were able to recontact 97 percent of the original sample of addicts who were prescribed heroin at London clinics in 1969. The interviews covered current and past legal and illegal drug taking, as well as various personal, social, and medical aspects of drug addiction. The statistics presented here document changes in drug use for the entire sample, focusing on the proportion of persons were received prescriptions for heroin or who were on methadone maintenance, the pattern of drug use among persons who stopped attending the treatment clinics, the institutional status of the sample, and the number of months spent in employment and other activities. 4 figures and 6 references