Abstract: The problem of inflammatory diseases of the small organs is very urgent, since pathology is registered in 60-65% of women of reproductive age, this indicator has no tendency to decrease. Inflammatory diseases of the pelvic organs have an extremely adverse effect on reproductive potential, occupying a leading place in the structure of the causes of female infertility, forming a negative dynamics of demographic indicators in the state, which allows us to consider this problem not only as a medical, but also as a social one. This article highlights the main etiological factors of inflammatory diseases of the pelvic organs, among which the leading role belongs to the bacterial – viral – mycotic association (Chlamydia trachomatis, Neisseria gonorrhoeae, opportunistic microorganisms (Esherichia coli, Mycoplasma hominis, Ureaplasma urealiticum, Gardnerella vaginalis), HSV type 1 and HSV type 2, CMVI, virus Epstein – Barr, HPV, HIV). Various pathogenetic mechanisms of the impact of microorganisms on the organs of the reproductive system are also highlighted: stimulation of pathoimmunological and pathomorphological changes in the endometrium that prevent the adhesion and implantation of blastocysts and the development of trophoblasts, changes in the receptor field of the endometrium, increased secretion of antisperm antibodies that activate sperm agglutination, which prevents their advancement through the female genital tract, capacitation and fertilization. Some infectious agents are able to adsorb on the surface of spermatozoa, reduce their mobility and prevent penetration. The complex of these influences determines the formation of structural and functional prerequisites for the development of infertility. Inflammatory diseases of the pelvic organs are characterized by latent or abortive variants of the course, which significantly complicates their diagnosis at early stages and the appointment of timely and optimal therapy. It is important to note that inflammatory diseases of the reproductive organs can lead to infertility, but also significantly reduce the successful outcome of the use of assisted reproductive technologies.