Infertility is one of the most increasing health problems of the population. Endometrial structure and receptivity are among the most significant factors for successful embryo implantation and pregnancy development. Nevertheless, the available data on the regulation of endometrial function and its structure in conditions of hormonal and metabolic dysbalance are insufficient. This makes it necessary for deeper research of the human endometrium in these fields. In the review we analyzed the genetic and epigenetic changes of the endometrial tissue, presented modern ideas about the cellular and tissue levels of regulation of normal endometrium and their changes in patients with polycystic ovarian syndrome (PCOS). Modern diagnostic markers of endometrial dysregulation are also considered. However, it is noted that further research is required to develop clear diagnostic algorithms and therapeutic effects aimed at improving reproductive outcomes in PCOS.