The co-occurrence of alcoholism and depression was examined in 201 opioid addicts and their 877 first-degree relatives using direct interviews and structured family history based on the Schedule for Affective Disorders and Schizophrenia (SADS) Research Diagnostic Criteria (RDC) method. Familial alcoholism was more frequent in alcoholic than nonalcoholic proband addicts, and primary depression was more frequent in relatives of depressed than nondepressed addicts. An association was suggested between secondary, but not primary, depression and alcoholism in females.