Purpose: To investigate the diagnostic accuracy of endometrial curettage in patients with endometrial carcinoma. In this retrospective study, pre- and postoperative histopathologic findings of patients with endometrial cancer were investigated. Methods: 168 patients with the final diagnosis of endometrial cancer were enrolled in the study. Pre- and postoperative histopathologic diagnoses and grades (according to the 1988 FIGO classification) of the patients were compared retrospectively. Results: 22 patients were diagnosed as having endometrial hyperplasia and the remaining 136 patients had endometrial carcinoma preoperatively. Overall discrepancy rate of grades was 39% (31% upgrade, 8% downgrade; p < 0.05). There was also 9% discrepancy between the pre- and postoperative histopathological types. Conclusion: It has been suggested that since endometrial cancer patients with low grades according to the preoperative pathologic diagnosis have a potential to upgrade, the management of these patients if myometrial invasion is less than one-half thickness, simply by hysterectomy plus bilateral salpingo-oophorectomy (without lymph node sampling), might actually miss some patients who actually deserve surgical staging. Further studies are needed to draw a sufficient conclusion.