Objective: To evaluate uncommon types of borderline ovarian tumors (BOT) and define the clinical, surgical, and pathologic features.Material and Methods: Seventeen patients who were treated in our hospital between 1990 and 2017 were identified. Patients’ data werecollected from the gynecologic oncology clinic electronic database, patients’ files, and pathology reports. Conservative surgery was defined aspreservation of the uterus and at least part of one ovary.Results: The mean age was 47 (range, 22-70) years. Based on histopathologic tumor type, there was mixed tumor in five (29.4%) patients,endometrioid-type in nine (52.9%), seromusinous-type in two (11.8%), and Brenner-type in one (5.9%). Conservative surgery was performed in4 patients. Two patients with endometrioid BOT had synchronous endometrial pathology, including one (11%) patient with endometrial cancer,one (11%) with endometrial hyperplasia without atypia, and 3 (33%) patients had endometriosis. The median follow-up was 19 (range, 1-137)months. No recurrence was observed during the follow-up period.Conclusion: In our small volume case series, it could be said that non-serous/non-mucinous BOT has excellent prognosis. However, endometrialpathology should be checked in endometrioid type