A total of 1300 patients were examined; this number included patients suffering from food poisoning and with suspected dysentery hsopitalized at the isolation hospital; patients with diarrheal diseases under observation of the intestinal unit of the sanitary-epidemiological station, and patients with acute or exacerbation of chronic affection of the bile tracts. A total of 28 Yersinia enterocolitical strains were isolated from these patients, this constituting 2.1% of the total number os examinations. The strains isolated were typical by ciological properties and were referred to the 3rd and 9th serological and the 3rd and 4th biochemical types.