One hundred eighty-six cases of ovarian common "epithelial" tumor including 28 endometriosis were reviewed, from the pathology file of the department of pathology of the National Medical Center during a period of 8 years and 6 months from January 1976 to June 1984. The study consisted of 14 cases(77.4%) of benign tumor including 28 cases of ovarian endometriosis, and 21 cases(11.3%) of borderline malignancy and 21 cases(11.3%) of invasive malignant tumors. Among benign common "epithelial" tumors, mucinous cystadenoma(69 cases) was the most frequent tumor, followed by serous cystadenoma (42 cases) and Brenner tumor (5 cases). Of borderline tumor, borderline mucinous tumor (18 cases) was more frequent than serous tumor (3 cases). Serous cystadenocarcinoma(9 cases) was the most frequent malignant tumor, followed by mucinous cystadenocarcinoma(6 cases), endometrioid carcinoma(3 cases) and undifferentiated carcinoma(3 cases). Most ovarian common "epithelial" tumors were prevalent during the reproductive age, but malignant tumors were more prevalent after the age of 40. Although right side was more frequently found (85 vs. 67) there is no significant site predilection. Bilaterality was the most common in undifferentiated carcinoma(66.7%), followed by serous cystadenocarcinoma(44.4%) and Brenner tumor(40%). The size of tumor tended to be larger in malignant tumor than benign. Mucinous tumor were usually larger than serous tumor. There were 7 intrauterine and 1 ectopic tubal prognancy which were associated with ovarian common "epithelial" tumors. Three cases of tumors were excised during Cesarian section. In summary these findings are comparable to other reports in Korea and English literatures. Histologic analysis of borderline and malignant epithelial tumor was done to emphasize their biologic behavor. Further study is required to compare their histological grading and clinical staging with thier survival rate.