Abstract Background and Aims Chronic pyelonephritis in the structure of extragenital pathology in pregnant women occupies a leading place due to the high prevalence, complicated course of pregnancy and childbirth. Chronic pyelonephritis (CP) triggers a cascade of reactions, primarily immune, at the systemic and local levels. With HP the role of the immune system in pregnant women is not only a pathological process occurring in the kidneys, but also takes into account a number of changes in the restructuring of the immune system of a pregnant woman. In relation with the above, the study of the role of the immune system of pregnant women with chronic pyelonephritis is of great interest. To study the effectiveness of immunocorrective therapy in the complex treatment of patients with chronic pyelonephritis. Method 43 pregnant women with CP were examined, the average age was 28.3 ± 0.2 years. The study included clinical research methods (survey, questionnaire, objective examination). Of the laboratory methods a general analysis of blood, urine, urine analysis according to Nechiporenko, tank. urine culture, biochemical blood tests and instrumental (ultrasound) research methods. Cellular immunity was studied by monoclonal antibodies, humoral immunity was studied by Mancini immunodiffusion. Among the surveyed women, the first group of upp was pregnant women (n = 14) receiving traditional therapy. The second group of 13 pregnant women with CP on the background of traditional therapy received ozone therapy (basic treatment + 400 ml of saline solution ozonated to a concentration of ozone in a liquid of 4 mg/l, intravenously, drip). The third group of 15 pregnant women with CP - with traditional therapy received ozone therapy and immune-regulating therapy with polyoxidonium. Results The characterization of clinical and laboratory data on the background of therapy showed significant shifts, as lower back pain decreased by 85.71%, 92.31% and 93.33%, respectively, in both the first and second and third groups. Indicators such as dysuria decreased by 92.85%, 92% and 93% (respectively in the first, second and third groups). Leukocyturia decreased significantly on the fifth day by 71.43%, 84.62%, 86.67% (in the first, second and third groups, respectively). Results indicators of eradication of pathogens after treatment in combination with traditional therapy with ozone and immune-correcting therapy, they were significantly better than in the ozone therapy group against the background of traditional therapy and in the traditional treatment group (86.6%, 84.6% and 64.28%, respectively). As a result of the study, significant decreases in cellular immunity indicators, in particular CD3, CD4, were revealed before the treatment of patients and CD8 and revealed a significant increase in IgA, IgM. After the treatment in the treatment group in combination significant increases in the number of CD3, CD4 and CD8 were revealed by traditional therapy with ozone- and immune-regulating therapy (by 76.1%, 64.68% and 58.3%, respectively), compared with the group of women who received only ozone therapy against the background of traditional therapy and in the group of traditional treatment (66.23%, 59.54%, 54.2% and 61.12%, 54.68%, 51.4%, respectively), and normalization of immunoglobulins A was noted and M. Conclusion Along with the improvement of clinical and laboratory data in CP normalization of cellular and humoral immunity indicators was noted in pregnant women. Additional assignment to traditional therapy for chronic pyelonephritis of pregnant women, ozone therapy and therapy for correction of the immune system is a more effective treatment method.