In the treatment of endometrial cancer, surgical treatment, radiotherapy, chemotherapy, and hormonal therapy are available. Since endometrial cancers are adenocarcinoma with a relatively low response to irradiation in most a cases, surgical operation is the first choice in these cases. The operative procedure is chosen according to the cancer staging currently used in Japan (FIGO, 1982), because it is a preoperative staging. In principle, total hysterectomy is done for cases of stage 0, modified radical hysterectomy for stage I, radical hysterectomy for stage II, and radical hysterectomy combined with resection of the metastatic lesions for stage III and IV. In addition, adnexa has to be resected bilaterally. In cases of stage II or higher stages, resection of para-aortic lymph nodes is done in addition to pelvic lymphadenectomy according to the depth of myometrial invasion and histologic type. On the other hand, the new international corpus cancer staging employed by FIGO in 1988 is a surgical staging which determines the stage on the basis of the intraoperative and postoperative histopathological findings. This staging takes into account more prognostic factors, reflecting the prognosis more precisely. In the near future, the Japan Society of Obstetrics and Gynecology will introduce a new staging. Since this staging is, however, determined postoperatively, it cannot be a criterion for choosing operative procedures. In addition, it is well known that preoperative diagnosis is not always consistent with intraabdominal findings. Therefore, it is important to determine most appropriate operative procedure by checking preoperatively the prognostic factors such as histopathology, degree of differentiation, cervical involvement, myometrial invasion and presence or absence of extrauterine progression precisely as far as possible. At the same time, by taking into consideration the intraoperative findings, an extended operation not limited to the above mentioned procedures should be undertaken in cases with higher risk factors.