Objective: To study what are the prognostic factors of lymph nodes (LN) metastasis in all types of high-grade endometrial carcinoma (EC): poorly differentiated endometrioid carcinoma (ECG3), clear-cell carcinoma (CCC), uterine serous carcinoma (USC), and carcinosarcoma (CS). Materials and Methods: A multicentric, retrospective cohort study including 252 patients with lymphadenectomy (LND) (pelvic and /or para-aortic). The authors assessed the predictive value for LN metastasis of myometrial invasion, lymphovascular space involvement (LVSI), isthmus affectation, tumor size, presurgical CA 12.5 value, Ki67 expression, and p53 immunohistochemistry in samples from hysterectomy. Results: Of the 252 patients with high-grade EC that were included in the study, 94 had ECG3, 69 USC, 43 CCC, and 46 CS. Pelvic LND was performed in 248 (98.4%) patients and para-aortic in 111 (44%). No significant differences were observed in the number of LN resected according to their histological subtype (p = 0.161; para-aortic, p = 0.051). The authors found positive LN in 79 (31.3%) of the 252 patients. Deep myometrial invasion (OR 6.006 IC 95%: 2.715-13.287, p ≤ 0.001), LVSI (OR 11.805 IC 95%: 5.829-23.907, p ≤ 0.001), isthmus affectation (OR 5.481 IC: 95% 2.743-10.952, p ≤ 0.001). and abnormal presurgical CA 12.5 value (p = 0.006) were significantly associated with the presence of metastasis confirmed by histological examination. The remaining factors included in the study were not observed to have any predictive value for LN metastasis. Conclusions: Myometrial invasion, LVSI, uterine isthmus affectation, and preoperative value of CA 12.5 were found to be predictor factors of LN metastasis in high-grade EC. Tumor size, Ki67 expression, and p53 were not observed to have any predictive value for LN metastasis.