The aim of this study was to evaluate the clinicopathologic findings of twelve patients with Brenner tumor of the ovary diagnosed and treated in the department of Gynecology and Obstetrics, University of Ulsan, Asan Medical Center for nine years. Demographic characteristics, symptoms, signs, stage, tumor grade, mode of therapy and results of follow-up were reviewed retrospectively. The patients with Brenner tumor constituted 0.54% of all epithelial ovarian tumor ecountered during this period. The age of patents ranged from 47 to 79 years (mean+/-S.D.; 60.1+/-11.9) and the mean parity was 3.3. Eleven cases except one, who had FIGO stage Ia disease, had benign tumors. The tumor size ranged from 0.5 to 12 cm (mean+/-S.D.; 4.8+/-3.8 cm). Uterine adenomyosis was the most frequently associated disease (58.3%) and all tumors were unilateral. Total abdominal hysterectomy with unilateral or bilateral salpingoophorectomy were performed in all patients and no further postoperative adjuvant treatments were done even in the patient with malignant tumor, who is alive without evidence of disease.