Forty patients with 50 ovarian epithelial tumors of the ovary were retrospectively studied. They underwent computed tomography and magnetic resonance (MR) imaging within 1 week of surgery. MR examinations were performed with a superconducting magnet (0.5 T) and predominantly T1- and T2-weighted MR imaging. T1-weighted MR images were obtained in eight patients after contrast material was administered. Signal intensity of tumors was compared with that of urine, muscle, and fat. Morphologic features that were evaluated included size, vegetations, septations, wall thickness, fluid or solid components, and vascularity. On the basis of signal intensity and morphologic characteristics, MR imaging helped in the correct diagnosis of benign serous cystadenoma in 10 of 13 tumors, benign mucinous cystadenoma in seven of 10 tumors, and tumors of low malignant potential and malignant tumors in 23 of 27 tumors. Accuracy for overall characterization of benign versus malignant tumors was 86% with MR imaging and 92% with computed tomography. There was no difference in sensitivity (P = 1) or specificity (P = .5).