Objectives: The aim of this study was to evaluate the usefulness of concurrent transcervical resection and total curettage (TCR+C) for patients in whom a definitive preoperative pathological diagnosis of the presence or absence of endometrial cancer (EC) could not be obtained. Materials and Methods: A total of 125 patients who underwent curettage with office hysteroscopy (63 patients) or TCR+C (62 patients) for suspected uterine malignancy were retrospectively reviewed by focusing on pathologic and hysteroscopic findings. Furthermore, the pathological diagnostic accuracies of EC between curettage alone and TCR+C were analyzed in 29 EC patients who received hysterectomy. Results: Six of 12 suspected EC patients (50%) who underwent curettage alone had a discrepancy in the final diagnosis by hysterectomy; meanwhile, 15 of 17 suspected EC patients (88.2%) were accurately diagnosed as EC by TCR+C before hysterectomy. In total, TCR+C provided significantly more accurate pathological diagnosis of EC than curettage alone with office hysteroscopy (p = 0.038 by Fisher’s exact test). In addition, hysteroscopic findings showed that all resected specimens of white desquamation lesions with atypical branched vessels in the endometrium were diagnosed as endometrial cancer. No significant adverse effect was observed in TCR+C group. Conclusions: Endometrial diagnosis with TCR+C is a more useful technique for suspected EC lesions than curettage alone.