Patients (179) with endometrial carcinoma underwent hysterography as part of their pretreatment evaluation. Women (126) received preoperative irradiation followed by hysterectomy; 30 had surgery alone; while 23 received radical radiotherapy. Hysterograms were classified by the degree of tumor invasion suggested radiographically and these were compared, in the operated cases, with postoperative pathologic examination. Lesions confined to the endometrium, or with superficial myometrial penetration, demonstrate no radiologic abnormality or a small, shallow defect by hysterogram. In those patients with deep myometrial invasion of cancer, hysterograms usually demonstrate a large defect in the endometrial cavity. Hysterography helps assure optimum treatment of each individualized case by helping to determine the volume of tumor and extension into the myometrium.