In the Early Stages (ES) of Borderline Ovarian Tumor (BOT), if surgery without risk of tumor rupture is possible, then laparoscopy with protected extraction is recommended over laparotomy (Grade C). In case of bilateral serous ES BOT treatment with a strategy to preserve fertility and/or endocrine function, bilateral cystectomy is recommended if possible (Grade B). In case of mucinous BOT treatment with a strategy to preserve fertility and/or endocrine function, unilateral adnexectomy is recommended (grade C). In the case of a mucinous BOT in a patient who has had an initial cystectomy, unilateral adnexectomy is recommended (grade C). In the case of treatment of a serous ES BOT in a patient who has had an initial cystectomy, with a strategy to preserve fertility and/or endocrine function, restaging surgery for adnexectomy is not recommended in the absence of suspicious residual lesions at the time of surgery and/or postoperative imaging (reference ultrasonography or pelvic MRI) (grade C). For serous or mucinous ES BOTs, routine hysterectomy is not recommended (Grade C). In cases of ES BOTs, lymphadenectomy is not recommended (Grade C). For ES BOTs, appendectomy is recommended only if there is a macroscopically pathological aspect to the appendix (Grade C). Restaging surgery is recommended in case of a serous BOT with a micropapillary aspect and an unsatisfactory inspection of the abdominal cavity during initial surgery (Grade C). Restaging surgery is recommended in cases of mucinous BOT if only a cystectomy has been performed or if the appendix has not been evaluated (Grade C). If restaging surgery is decided for an ES BOT, the following procedures should be performed: peritoneal cytology (grade C), omentectomy (there is no data in literature to recommend which type of omentectomy should be performed) (grade B), complete exploration of the abdominal cavity with peritoneal biopsies (grade C), visualization of the appendix +/- appendectomy in case of pathological macroscopic appearance (grade C) and unilateral adnexectomy in case of a mucinous BOT (grade C). In advanced stages of BOT it is not recommended to perform a lymphadenectomy as a routine procedure (Grade C). In cases of an advanced stage BOT, in a patient with a desire to fall pregnant, conservative treatment involving preservation of the uterus and all or part of the ovary may be proposed after a multidisciplinary meeting (Grade C). Second surgery aimed at removing all lesions, if not performed initially, is recommended in cases of advanced stage BOT (Grade C). It is not recommended to perform completion surgery after conservative treatment (preservation of the ovaries and the uterus) and after the achievement of fertility desire for a serous BOT (Grade B). After treatment for a BOT, follow-up beyond 5 years is recommended due to the median time to recurrence (Grade B). It is recommended that a systematic clinical examination be carried out during follow-up of a treated BOT (Grade B). In the particular case of an initial elevation of CA 125 levels, it is recommended to monitor CA 125 during follow up (Grade B). In cases treated conservatively (ovarian and uterine conservation), it is recommended to use endovaginal and transabdominal ultrasonography during the follow up period (Grade B). In the event of a recurrence of a BOT, in a woman of childbearing age, a conservative treatment strategy can again be proposed (Grade C). In the presence of non-invasive BOT implants, conservative treatment may be considered after a first non-invasive recurrence in women who wish to preserve their fertility (Grade C). Pelvic MRI is recommended after 12 weeks of amenorrhea in case of an undetermined adnexal mass and should be concluded with a diagnostic score (Grade C). The injection of gadolinium, in case of pregnancy, should be discussed on a case-by-case basis due to the proven risks for the foetus (Grade C). If feasible, a laparoscopic approach should be preferred during pregnancy (Grade C). A consultation with a specialist reproductive physician should be offered to patients with a BOT and of childbearing age (Grade C). It is recommended that patients be provided with full information on the risk of decreased ovarian reserve following to surgical treatment. It is recommended that the ovarian reserve be evaluated prior to surgical management of a suspected BOT (Grade C). When possible, a conservative surgical strategy is recommended to preserve fertility in women of childbearing age (Grade C). There is no specific data on the management of infertility following to conservative treatment of BOT. In case of durable infertility following to conservative treatment of BOT, a consultation with a specialist reproductive physician is required (Grade C). In the case of optimally treated BOT, there is no evidence in literature to contraindicate the use of Assisted Reproductive Techniques (ART). The use of hormonal contraception after serous or mucinous BOT is not contraindicated (Grade C). After treatment of a mucinous BOT, for women aged under 45 years, given the benefit of hormonal replacement therapy (HRT) on cardiovascular and bone risks, and the lack of hormone-sensitivity of mucinous BOTs, it is recommended to offer HRT (Grade C). After treatment of a mucinous BOT, for women over 45 years of age, there is no argument to contraindicate the use of HRT. HRT can be prescribed in case of a climacteric syndrome, as part of an individual benefit to risk assessment (Grade C).