We studied the effect of prior narcotic addiction on response to treatment of alcoholism. Patients in the Elmhurst Alcoholism Treatment Program are offered medical care, counseling, disulfiram, and close affiliation with Alcoholics Anonymous. We compared 85 alcoholics who had a history of narcotic use with a control group of 85 alcoholics matched for age, sex, and race who had never used narcotics. Among controls, 30 (35%) became abstinent from alcohol for at least half the time that they were known to us. Of the former narcotic users, only 8 (9%) became abstinent for at least half the time they were known to us. Former narcotic users did poorly in alcoholism treatment, whether or not they had ever been treated with methadone maintenance. Alcohol use. often heavy, began before heroin use in at least half the narcotic group. We conclude that a history of narcotic use reduces markedly the chance of success in conventional alcoholism treatment, and that alcoholism and narcotic addiction develop independently.