Radiologic findings of 17 cases of pathologically-proven endometrioid carcinoma of the ovary were retrospectively analyzed. The radiological examinations included were CT scans in 13 patients sonograms in 13 patients, and MR imaging in one patient. The tumor involved both ovaries in 11 patients(65%). Ascites was noted in 12 cases(70%). The consistency of the tumors evaluated by radiological findings varied from purely solid(n=4) to predominantly solid(n=11) or predominantly cystic(n=4). There was no case with the purely cystic type. The most common radiological finding of the endometrioid carcinoma of the ovary was lobulated ovarian masses of predominantly the solid type often inseparable from the outer margin of the uterine body. MR imaging was helpful in differenciating various components of an intermingled pelvic mass on CT, i.e., tumor mass, uterus, and ascites. In one case, there was associated endometrial carcinoma of the uterus. We believe that familiarity with these radiological findings of endometrioid carcinoma of the ovary will be helpful for preoperative differential diagnosis of ovarian masses.