Introduction: We retrospectively evaluated the performance of preoperative computed tomographic (CT) colonography to detect tumor involvement of the rectosigmoid wall and predict the need for rectosigmoid resection in patients with primary ovarian cancer. Methods: Thirty-three patients with primary ovarian cancer who underwent preoperative CT colonographic examination were evaluated. The images of the examination were analyzed and compared with the Subsequent surgical findings. Results: All abnormal findings (malignant infiltration of the rectosigmoid mucosa and extrinsic compression) revealed by conventional colonoscopy were correctly observed as extrinsic compression using CT colonography. The sensitivity, specificity. positive predictive Value and negative predictive value of CT colonography for the prediction of rectosigmoid resection were 100%. 64.7%, 72.7%. and 100%, respectively. Though conventional colonoscopic examinations Could not be completed in five patients because of the presence of extrinsic stenosis and occlusion at the sigmoid colon, CT colonography enabled the entire large bowel to be examined in these patients. Conclusions: This preliminary study showed that the CT colonographic examination is feasible and safe. CT colonography seems to have several advantages over conventional colonoscopy for (he detection of rectosigmoid involvement in patients with advanced ovarian cancer. For confirmation of the efficacy of CT colonography. Further large prospective Studies are needed.