Inflammatory diseases of the pelvic organs (PID) occupy the first place in the structure of gynecological morbidity and are one of the causes of dysfunction of not only the reproductive organs but also various systems of the female body, infertility, and a decrease in the quality of life. The PID includes inflammatory processes of the uterus, fallopian tubes, ovaries and pelvic peritoneum. The article presents modern views on etiological factors, stages of development of endogenous infection and its clinical manifestations. The mechanisms of endocrine and immune regulation of the vaginal microbiocenosis, as well as the relationship of endogenous microflora and pathogens of exogenous genital infections, are examined. Diagnostic approaches and principles of treatment of PID are presented, taking into account the severity of the infectious process. Key words: рelvic inflammatory diseases, salpingitis, endometritis, microbiocenosis, sexual exinfection, diagnosis, treatment principles.