Background and Objectives: The purpose of this study was to find out the risk factors associated with non-sentinel lymph node metastasis and determine the incidence of non-sentinel lymph node metastasis according to risk groups in sentinel lymph node (SLN)-positive endometrial cancer patients. Methods: Patients who underwent at least bilateral pelvic lymphadenectomy after SLN mapping were retrospectively analyzed. Patients were categorized into low, intermediate, high-intermediate, and high-risk groups defined by ESMO-ESGO-ESTRO. Results: Out of 395 eligible patients, 42 patients had SLN metastasis and 16 (38.1%) of them also had non-SLN metastasis. Size of SLN metastasis was the only factor associated with non-SLN metastasis (p =.012) as 13/22 patients with macrometastasis, 2/10 with micrometastasis and 1/10 with isolated tumor cells (ITCs) had non-SLN metastasis. Although all 4 metastases (1.8%) among the low-risk group were limited to SLNs, the non-SLN involvement rate in the high-risk group was 42.9% and all of these were seen in patients with macrometastatic SLNs. Conclusions: Non-SLN metastasis was more frequent in higher-risk groups and the risk of non-SLN metastasis increased with the size of SLN metastasis. Proceeding to complete lymphadenectomy when SLN is metastatic should further be studied as the effect of leaving metastatic non-SLNs in-situ is not known.