Purpose : To assess the value of CT for the differential diagnosis of malignant ovarian tumors. Materials and Methods : We reviewed CT scans of 31 patients with surgically confirmed 46 malignant ovarian tumors. (29epithelial tumors, 9 Krukenberg tumors, 6 germ cell tumors, and 2 sex cord-stromal tumors.) CT scans were evaluated for the mass (bilaterality, size, internal component, and margin), peritoneal spread pattern, ascites, invasion of adjacent organ, and lymphadenopathy. Result : Bilateral masses were seen in epithelial or Krukenberg tumor in 61.1%(11/18) and 80%(4/5) respectively. Epithelial tumors showed predominantly cystic mass(37.9%, 11/29),irregular margin(82.8%, 24/29) of mass, and accompanying peritoneal and omental spread (66.7%, 12/18), while Krukenberg tumor showed predominantly solid mass(55.5%, 5/9), smooth margin of mass(100%, 5/5), and no peritoneal and omental spread. All cases with germ cell tumor or sex cord-stromal tumor showed unilateral mass. Relatively young aged, unilateral solid (66.7%, 4/6) tumors were germ cell tumor. Of these cases, septa within solid portion of mass were prominent in all dysgerminoma. (3/3) Conclusion : CT may be a valuable tool for the differential diagnosis of malignant ovarian tumors.