Computed tomography (CT) and 67Ga-citrate computer scintigraphy (67Ga-CS) were carried out on 184 patients with ovarian tumors. CT(EMI scanner model 5005/12 or General Electric model CT/TX-2) was performed in 169 cases and 67Ga-GS in 128, after visualization and calculation by computer. In 113 cases diagnosis was made with the combined use of both methods and CT number and ROI counts in 67Ga-CS were obtained. Dermoid cysts were easily detected by their characteristic CT image and CT number. The mechanism by which 67Ga accumulated in malignant tumors was investigated and 67Ga was found mainly in microsome and mitochondria fractions of the cell, and bound to protein with a molecular weight of about 70,000 daltons. The accuracy and clinical evaluation of CT, 67Ga-CS and their combined use were compared to those of bimanual pelvic examination. The diagnostic accuracy in differentiating between cystic and solid tumors was 77.9% by bimanual, 85.8% in CT, 75.2% in 67Ga-CS and 87.6% in combined use. The accuracy in differentiating between benign and malignant tumors was 74.3%, 88.5%, 92.0% and 94.7% respectively. The combined use of CT and 67Ga-CS could guarantee higher accuracy in diagnosis than bimanual pelvic examination, and was considered to be a valuable diagnostic method.