Endometrial cancer is the most common gynecologic malignancy. Primary surgery, including hysterectomy, bilateral salpingo-oophorectomy, and retroperitoneal lymph node dissection, is the standard procedure for endometrial cancer. The status of lymph node metastasis is important in determining clinical stage and the suitability for postoperative therapy. Pelvic and para-aortic lymph node dissection is necessary for accurate diagnosis of lymph node metastases. Some patients truly have lymph node metastases, but most patients undergo unnecessary lymph node dissection, which results in postoperative lymphedema and lymphangitis of the lower extremities. The sentinel lymph node (SLN) is the first lymph node to receive flow from the primary tumor. An SLN biopsy without systematic lymph node dissection can reduce surgical morbidities such as lymphedema, lymphocyst, and lymphangitis. It has been reported that SLN biopsies have a high detection rate, sensitivity, and negative predictive value in patients with endometrial cancer. Several studies suggest that an SLN biopsy is an effective treatment strategy and there is no significant difference between an SLN biopsy and lymphadenectomy in oncologic outcomes for the patients with endometrial cancer. Prospective randomized trials involving SLN biopsies in patients with endometrial cancer are ongoing, and promising results are expected.