A prospective evaluation of computed tomography and ultrasound was performed on 24 consecutive patients with suspected pelvic masses. Of the 24 patients, 22 had subsequent surgical identification of abnormalities; two were considered normal on clinical follow-up. Ultrasound provided important clinical information in 17 of 24 patients; CT in 15 of 24 patients. There were three false negative examinations with each method and no false positives. Differentiation between benign and malignant disease could not be made in four of 24 patients by ultrasound and five of 24 patients by CT. Because both imaging techniques depict similar pathology and use similar diagnostic criteria, the two methods tend not to be complementary.