Objective. Thegoal of this study was to determine the influence of LVSI (lymphvascular space involvement) on the risk of lymph node metastases from endometrial cancer.Methods. All patients with surgically staged endometrial cancer from 1998 to 2000 were identified from divisional databases. The influence of LVSI on the risk for nodal metastases was determined after controlling for tumor grade and depth of invasion, and comparisons were made with the chi(2) or Fisher's exact tests. Multivariable analysis was performed using a logistic regression model.Results. We identified 366 patients who fit the study criteria. Pathologically, 92/366 (25%) tumors had LVSI, and 46 patients (13%) had evidence of pelvic lymph node metastases. Cancers with LVSI were significantly more likely to have nodal disease (35/92 versus 11/274, P < 0.001). When controlled for tumor grade, the presence of LVSI led to an increased incidence of pelvic node metastases (P < 0.001 for all grades). When stratified by depth of invasion in thirds, the presence of LVSI led to a significantly increased chance of pelvic lymph node metastases (P < 0.05 for each strata). When tumor grade and depth of invasion were evaluated together, LVSI led to a significantly increased risk of pelvic node metastases in patients with deeply invasive tumors. In a multivariable analysis, LVSI led to a significantly increased risk for pelvic lymph node metastases (P < 0.05).Conclusion. LVSI leads to an independent and significantly increased risk for pelvic lymph node metastases. As such, the presence of LVSI may indicate the need for lymphadenectomy or adjuvant therapy for potential regional lymph node metastases in patients with unstaged endometrial cancer.