Secretion of some IL and growth factors (VEGF, IGF-I, TGFβ) by endometrial tissues and endometrioid heterotopies was studied in vitro in patients with external genital endometriosis of different severity. The production of IL-1β, IL-2, IL-6, and VEGF in the endometrium increased in severe external genital endometriosis, while the secretion of TGFβ decreased; hyperproduction of IL-2, IL-6, VEGF and decreased production of TGFβ were detected in endometrioid foci. Presumably, local cytokine imbalance and increased proliferative activity of endometrial cells are involved in the mechanisms of formation and functioning of endometrioid foci.