Introduction/Background The aim of this study was to compare the oncologic outcomes in stage I borderline ovarian tumors (BOTs) patients treated with unilateral ovarian cystectomy (UOC) versus unilateral salpingo-oophorectomy (USO). Methodology This was a retrospective study of 95 patients with stage I BOTs treated with cystectomy (n=22) or unilateral salpingo-oophorectomy (n=73) between 2000 and 2017 at Keimyung University Dongsan Medical Center. The surgical and oncologic outcomes between the two groups (UOC versus USO) were compared. Results After a median follow-up of 76 months (range: 10–215), there were 9 patients who had recurrences (UOC group: 4 vs. USO group: 5). The recurrence rate was higher in UOC group (18.2%) than in the USO group (6.8%). However, there was no statistically significant difference in recurrence rates (p=0.104) and 5-year progression free-survival (p=0.099) between the two groups. All recurred patients except 1 patient (USO group) were successfully treated by secondary operation and were alive with no clinical evidence of disease. Only 1 patient was died due to disease. Conclusion Our results support that both surgical methods are an acceptable treatment for women with stage I BOTs. Although USO is an appropriate treatment for BOTs patients, a UOC can be considered for patients who wish to preserve fertility when a unilateral cystectomy is the only surgical method. Disclosure Nothing to disclose.