Objective: The pretreatment neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) have been reported to be useful as markers for prognostic factors and metastasis in several cancers. The aim of this study was to identify the predictor of lymph node (LN) metastasis by pretreatment NLR and PLR in patients with endometrial cancer. Methods: Medical charts of the patients with endometrial cancers that received primary surgery at our hospital between 2007 and 2013 were retrospectively analyzed. The cutoff value was calculated from the receiver operating characteristics (ROC) curve. Clinicopathological parameters including inflammatory markers were evaluated for LN metastasis using multiple logistic regression analysis. Results: Among 197 patients enrolled in the study, LN metastasis was observed in 25 patients (13%). ROC curves demonstrated that the best cutoff value of NLR for predicting LN metastasis was 2.18 and that of PLR was 206. In univariate analysis, several pathological factors, NLR, and PLR were identified as predictors of LN metastasis. In multiple logistic regression analysis, lymphovascular invasion and NLR were found to be significantly correlated with LN metastasis (p = 0.002, 0.039). Conclusion: A higher pretreatment NLR was identified as a predictor of LN metastasis in endometrial cancers. Although further study is needed to confirm the results, NLR could be a candidate clinical marker for detection of LN metastasis.