The examination of 265 patients with the diagnosis of acute enteric infection (AEI) of Klebsiella revealed that the disease took a mild course in 40%, a moderate course in 45.3% and a severe course in 14.7% of the patients. The clinical syndromes of acute gastritis, gastroenteritis, enteritis were observed; in cases of the severe course of AEI the hemolytic [correction of hemocolitic] syndrome was present. Immune shifts were characterized by T lymphopenia, a decrease in the number of T helpers/inductors (CD 4), the immunoregulatory indices (CD 4/CD 8), an increase in the level of circulating immune complexes. These levels reached their maximum in case of the severe course of Klebsiella infection and were retained till the patient was discharged from the hospital and, if any concomitant pathology was present, even for 1-3 months after discharge.