The novelty of our work was the analysis of the expression of miR-21, TGF-β1, SMAD3 and ILK in PBMCs obtained from women with diagnosed endometriosis compared to healthy ones in expectation of changes in the expression level profile of the studied genes/miRNA in connection with changes in the immune response (Treg and Th17 lymphocyte system). The gene discussed is TGFB1; the disease is endometriosis.