Objective: Genital endometriosis (GE) is a widespread gynecological disease which requires its further pathogenesis investigation and search for new effective treatments. The known data of oxytocin receptor presence in endometrioid heterotopy smooth muscle cells give some grounds to assume oxytocin participation in the pathogenesis of endometriosis. The present study objective was to evaluate oxytocin level in peripheral blood (PB) in patients with endometriosis associated pain syndrome and to estimate the efficacy of oxytocin receptor inhibitors (IOXTR) administration based on animal endometriosis model., Materials and Methods: The basic group comprised 61 patients with endometriosis associated pain syndrome, while 21 patients formed the control group. VAS, MPQ, and BBS objective tests were applied for pain syndrome evaluation. Oxytocin level in PB was measured by immunoenzyme method. After confirmation of endometriosis experimental model formation in rats and further randomization, a daily IOXTR intra-abdominal injection was performed in a dose of 0.35 mg/kg/24 h in the basic group ( n = 12) or saline solution administration in the control ( n = 12). On the final stage, endometrioid heterotopy size measuring was performed along with histological examination., Results: Oxytocin level in PB was authentically higher in patients with GE compared to the control: 51.45 (35.54-62.76) pg/mL and 27.64 (23.23-34.12) pg/mL, respectively ( p <.001). Positive correlation between oxytocin PB level and pain syndrome expression was established in patients with GE: VAS ( r = 0.76; p <.001), MPQ ( r = 0.52; p <.001), and BBS ( r = 0.57; p <.001). Based on the experimental disease model authentical decrease of endometrioid heterotopy average area was observed after IOXTR therapy compared to the control (7.3 ± 1.8 mm 2 and 22.2 ± 1.2 mm 2 , respectively, p <.05)., Conclusions: The obtained results confirm the oxytocin role in the pathogenesis of endometrioid associated pain syndrome. The high efficacy of IOXTR administration based on animal model of surgically induced endometriosis allows viewing this method as a perspective therapy.