Objective — to substantiate the efficiency of ozone and bacteriophage therapy in patients with chronic endometritis, by studying the morphological pattern and receptor properties of the endometrium. Subject and methods. A total of 100 patients aged 22 to 42 years with histologically verified chronic endometritis and a history of different reproductive dysfunctions were examined. Group 1 patients (n=50) underwent ozone therapy as intrauterine irrigation with ozonized isotonic sodium chloride solution, followed by the administration of complex pyobacteriophage into the uterine cavity as a 7-procedure cycle every other day and dropwise intravenous infusions of ozonized isotonic sodium chloride solution. A comparison group of 50 patients (Group 2) had traditional treatment with broad-spectrum antibiotics, vitamin complexes, trace elements, as well as physiotherapy. The impact of different treatment options on the morphological pattern and receptor properties of the endometrium obtained via pipelle biopsy during the implantation window was evaluated by histological and immunohistochemical techniques before and 2 months after treatment. Results. A histological examination of endometrial biopsy specimens established that all the patients had a set of typical signs of chronic endometritis; the expression level of sex steroid receptors (estrogens and progesterone) was reduced in both the endometrial glands and the stroma. Ozone and bacteriophage therapy resulted in decreased endometrial inflammatory response and restored receptor expression in Group 1. In Group 2, the positive changes were much less pronounced. Reproductive function was restored in a significant number of patients within 1.5 years. Conclusion. An improvement in endometrial morphofunctional parameters may be achieved by ozone and bacteriophage therapy used in the combination therapy of patients with chronic endometritis.