Three hundred male Irish alcoholics were selected from 508 consecutive alcoholic admissions to hospital. Using well defined diagnostic criteria, they were divided into three subgroups (1) primary alcoholics, (2) alcoholics with secondary affective disorder and (3) those with primary affective disorder and secondary alcoholism. Although the three groups reported differences in past history and family history of affective disorder and in time spent in hospital for both alcoholism and affective disorder, there was little to distinguish them in behaviour associated with alcoholism or in family history of alcoholism. The implications of these findings and their significance for the relationship of affective disorder and alcoholism are discussed.