Sera obtained from 642 patients with chronic alcoholism and 400 sera from healthy donors, collected in different regions of the USSR (Moscow, the Kirghiz SSR, Transcarpathian Province, the northern Caucasus), were studied. Out of all patients with chronic alcoholism whose blood sera were examined, persons aged 20-30 years constituted 22%, 31-40 years, 41.8%, 41-50 years, 27.5%, above 50 years, 8.7%. The results of the study of the immune structure of these patients with respect to the causative agents of respiratory diseases revealed a large proportion of persons seropositive to influenza virus B Leningrad/369/75 (92-93%) and coronavirus OC-43 (78-93%). Patients with chronic alcoholism were shown to belong to a high risk group with respect to Legionella pneumophila infection. The proportion of persons with antibodies to L. pneumophila among such patients (up to 21.1%) was considerably higher than among healthy donors (not more than 6%). In different regions of the USSR large risk groups with respect to diphtheria (42-56%) and tetanus (12-45%) were detected among patients with chronic alcoholism. These patients also showed considerably higher levels of anti-tissue antibodies in comparison with the healthy population.