Magnetic Resonance Imaging (MRI) has been widely used for the diagnosis of gynecologic disease. We studied the clinical usefulness of MRI in 34 patients with endometrial cancer from July, 1988 to August, 1991. Pre-operative pelvic MRI was carried out to evaluate the myometrial invasion in these patients. MRI was accurate in predicting the presence or absence of myometrial invasion in 23 of 34 cases (68%), while echo or CT (computed tomography) was accurate in 26% and 8%. In conclusion, MRI is considered to be the most useful examination for the evaluation of myometrial invasion in endometrial cancer.