The aim of the study — is to reduce the risk of ovarian endometriosis recurrence in women of reproductive age susceptible to the recurrence of endometriosis with the aid of an algorithm of observation and treatment of patients, based on the detection of its clinical and molecular-biological features. Material and methods. The histories of 147 patients of reproductive age with ovarian endometriosis and 28 patients with ovarian adenocarcinoma were retrospectively analyzed. Using histological and immunohistochemical methods, 78 and 35 observations of ovarian endometriosis were studied, respectively, and 8 observations of adenocarcinoma were studied using antibodies to the proliferative activity index (Ki-67), apoptosis inhibitor (Bcl-2), oncomarker (p53), and nuclear factor of hepatocytes-1β — HNF-1β. The data of 90 patients were prospectively analyzed. All patients underwent ultrasound examinations of the small pelvic organs with color Doppler mapping to determine the level of oncological markers CA-125, CA-19-9 and HE-4; 13.6% of patients underwent magnetic resonance imaging. Results. Patients with recurrent ovarian endometriosis have a higher incidence of somatic and gynecological diseases than patients with primary ovarian endometriosis. Epithelial atopy in endometriosis foci was revealed in 41% (6.4% — true atopy) of patients. Regardless of the presence of signs of epithelial atypia, HNF-1β hyperexpression is characteristic of ovarian endometriosis foci, which confirms the histogenetic connection between ovarian endometriosis and light-celled adenocarcinomas. In accordance with the results of the prospective study, an algorithm of observation and treatment of patients susceptible to ovarian endometriosis relapse has been developed. Conclusion. Correct interpretation of these radiological methods of diagnostics, and the results of histological and immunohistochemical examinations(with antibodies to Ki-67, Bcl-2, p53 and HNF-1β), along with the obligatory assessment of each patient’s history, allows us to predict the risk of recurrence and neoplastic transformation of endometriosis of the ovaries, and to then develop proper treatment guidelines.