Endometriosis is a widespread disease in which foci of tissue growth, morphologically and physiologically similar endometrium, are observed outside the uterine cavity. Earlier, we identified a number of genes that are overexpressed in ectopic endometrium compared to eutopic one. Among the genes overexpressed in the endometriotic lesions, four were particularly distinguished: C7, FABP4, ADH1B, and PLA2G2A. For all of them, differences in the expression level were multiples of 200–300. In this study, we verified the results obtained using RT-RV-PCR and IHC, and also conducted a study of the expression of these genes in the peritoneum of patients with endometriosis and healthy women. We have shown that a high level of expression of the studied genes is characteristic of endometriotic lesions and peritoneal cells, but not of eutopic endometrium. The FABP4, PLA2G2A and ADH1B proteins are known as adipogenesis markers, the C7 protein is also involved in the differentiation of adipose tissue stem cells. The equally