To differentiate between malignant and benign tumors, computed tomography (CT) and 67Ga-scintigraphy were carried out on 40 patients having pelvic masses. The uptake of 67Ga-citrate was divided into three groups: negative, suspicious and positive. Contrast enhancement (CE) was employed with CT. The increases in CT numbers after contrast enhancement were divided into three groups: no enhancement (0 to 20 HU), low enhancement (21 to 40 HU) and high enhancement (over 41 HU). The results were as follows: 67Ga negative group: out of 18 patients, there was only one patient with ovarian carcinoma. The lesion was too small to detect by CT. All the remaining 17 patients had benign tumors. The increased CT numbers in benign ovarian tumors were all within the range of no enhancement. On the other hand, the increases in CT number in myoma uteri were in the range of high enhancement. 67Ga suspicious group: in 3 of 10 patients, ovarian carcinomas were detected. Because the carcinoma tissues had low enhanced CT numbers after CE, they were easily differentiated from the benign tumors. 67Ga positive group: out of 12 patients, there were 3 patients with inflammatory disease. The increases in CT numbers in the inflammatory tissue were in the range of high enhancement, so they could be clearly differentiated from malignant tissues which ranged in low enhanced CT numbers. There were no benign tumors in this group.