An analysis of all deaths occurring over a 79-month period in patients enrolled in methadone maintenance (MM) revealed an overall mortality rate of 20/1,000. Over a similar period 510 persons were discharged from MM. Follow-up able to be performed in 80% revealed at least 22 deaths to have occurred subsequent to discharge. Survival curves calculated on the basis of these data indicate that even under the best possible assumption, age adjusted mortality rates of heroin addicts are not only above the national mean but are one and a half times that of the population in the community surrounding the clinic. None of the deaths could be directly attributed to methadone. Alcohol was prominent in 60% of all deaths, being responsible for 89% of medical deaths and present in 35% of violent deaths. These findings emphasize the persistent risk associated with heroin addiction as well as the role of alcoholism in the production of excessive mortality.