Introduction. Ovarian endometriomas affect 17 to 44% of women with endometriosis, and are often associated with pelvic pain and infertility, up to half of them have been recurred after surgery. Moreover, repeated surgery makes the ovarian reserve worse. The aim of our study was to investigate risks factors of recurrence of endometrioma. Methods. Immunohistochemical staining for progesterone receptor (PR), estradiol receptor (ER) and Ki67 was done with the fixed tissue blocks of their endometriomas which were collected at the time of surgery (after operation in aim to reduce adhesions we used Longidasa (Bovhyaluronidase Azoximer – conjugated enzyme, produced by NPO Petrovax Pharm, Russia, it is an advanced extended release enzyme used in a combined therapy of diseases associated with connective tissue hyperplasia). We had observed these patients during 1 year after operation and divided them into groups: without recurrence (69 women, group I) and with it (12 women, group II). Results. ER in I group was 1 points (1; 1), in second group was 1 (1; 2), PR was 3 points (3; 3), in II group was 3 (2; 3), Ki67 in stroma in I group was 2% (2; 2), in II group was 23% (20; 25), Ki67 in I group in gland was 7% (6; 9), in II group was 35% (30; 39). Mann-Whitney criterion U for independent samples reveals the statistical significance of Ki67 in stroma (p=0.0001) and Ki67 in gland (p=0.0001) between groups. In aim to find out the prognostic criteria of endometriomas recurrence we used ROC curve. According ROC analysis, if the expression of estradiol is more 1.5 points and Ki67 in gland is more 24.5%, we could expect recurrence of endometrioma (sensitivity 93.3%, specificity 100%). Conclusion. Expression of estradiol and Ki67 had significant correlation with recurrence of endometrioma. Ki67 expression at the time of first operation with subsequent recurrence was significantly higher than in non-recurred group in stroma and gland (p=0.001). For prognosis of recurrence we recommend to use ROC curve with using results of examination of estradiol and Ki67 in gland of endometrioma during first operation. However, to determine the possibility of immunoreactivity of estradiol and Ki67 as biomarkers for recurrent endometrioma, further studies of large numbers with prospective design are needed.