e16560 Background: To provide useful material for discussion, we report an analysis of a retrospective accrued, single-institution population with BOTs. Methods: 99 consecutive patients treated between April 1989 and July 2008, were reviewed for clinical characteristics, histology, surgical types, recurrence, and prognosis. Results: Median age was 46 years (19–77). 90% of patients were diagnosed by vaginal ultrasound as complex adnexal mass. CA-125 and CA19.9 was elevated in 60% and 30% of patients respectively. Primary treatment was surgery: laparotomy and laparoscopy (LT/LC) approach in 78% and 22% of patients, respectively. 33 patients (34%) underwent comprehensive staging operation; fertility-sparing surgery was performed in 18 patients (18%), and an incomplete staging in 47 patients (48%). The pathology results were: clear cell BOTs 1 case (1%); serous 42 cases (42.4%); mucinous in 56 women (56.6%) (46 intestinal/10 mullerian). 2 out of 56 mucinous BOTs were associated with pseudomixoma peritonei. Cyst-rupture was found in 22.5% and 38.9% of patients with LT/LC approach. 91women (93.8%) had stage I; 2 (2%) had stage II; and 6 (4.2%) had stage III disease. We identified 6 patients (7.8%) with noninvasive implants involving abdominal peritoneum (1), pelvic peritoneum (1), omentum (2) and both pelvic peritoneum and omentum (2). With a median follow-up of 3.6 years (0–18.4), we observed 5 recurrences (2 in contralateral ovary, 1 ipsilateral, 1 invasive peritoneal implant, and 1 para-aortic node). All were stage I disease at diagnosis. 2 out of 5 had incomplete staging, 3 had conservative surgery.3 cases were serous type. Histology recurrences were: 2 borderline, 2 invasive ovarian cancer, and 1 unknown. All patients underwent secondary cytoreduction achieving an optimal debulking in 4. Only one patient received chemotherapy. Two women died of intercurrent disease and 1 woman died of disease. The 5-year overall survival rate for entire cohort was 98.5% (95.6%-100%; CI95%). Conclusions: Our results confirm published data. Overall BOTs have an excellent prognosis. Proper staging is the cornerstone of treatment. Laparoscopy approach is associated with higher cyst rupture. Recurrences are more frequent after incomplete or conservative surgery. No significant financial relationships to disclose.