A clinicopathologic study of advanced ovarian carcinomas without an enlargement of the primary site has been performed. Cases studied were taken from 64 cases with a "common" epithelial tumor whose ovaries upon resection were directly measured for size. The ovaries of five cases (8%) were normal in size, and 3 (5%) of this number had been treated by chemotherapy prior to the resection of their ovaries. All three cases had been suspected to have an ovarian cancer at the start of treatment, one of these cases given a definite diagnosis of ovarian cancer, stage III, and the remaining two cases diagnosed as belonging to a special category. In these 3 cases, the ovaries had decreased in size and the primary cancerous site was difficult to determine, owing to the administered chemotherapy. A preoperative diagnosis of the remaining two of the 2 cases suspected an ovarian cancer in one, and a uterine corpus carcinoma, Ia in the other, associated with an ovarian cancer, stage III. These findings suggest that even though the enlargement of the ovaries was not to be remarkable, a laparotomy should be performed in cases strongly suspected of ovarian cancer, so as to ascertain the correct diagnosis by a careful inspection of the intraabdominal cavity, such as checking for the presence of ascites with malignant cells, or an elevated serum CA 125 without any other accountable primary foci.