BACKGROUND: The purpose of the current study was to determine the potential therapeutic role of lymphadenectomy in women with endometrioid corpus cancer. METHODS: Demographic and clinicopathologic information were obtained from the Surveillance, Epidemiology, and End Results Program between 1988-2001. Data were analyzed using Kaplan-Meier methods and Cox proportional hazards regression. RESULTS: In all, 12,333 women (median age, 64) underwent surgical staging with lymph node assessment, including 9,009, 1,211, 1,223, and 890 with Stage I-IV disease. Over the time intervals 1988-1992, 1993-1997, and 1998-2001, the percentage of patients undergoing lymph node staging increased from 22.6%, 29.6%, to 40.9% (P < .001). In the intermediate/high-risk patients (Stage IB, Grade 3; Stage IC and II-IV, all grades), a more extensive lymph node resection (1, 2-5, 6-10, 11-20, and >20) was associated with improved 5-year disease-specific survivals across all 5 groups at 75.3%, 81.5%, 84.1%, 85.3%, and 86.8%, respectively (P < .001). For Stage IIIC-IV patients with nodal disease, the extent of node resection significantly improved the survival from 51.0%, 53.0%, 53.0%, 60.0%, to 72.0%, (P < .001). However, no significant benefit of lymph node resection in low-risk patients could be demonstrated (Stage IA, all grades; Stage IB, Grades 1 and 2 disease; P = .23). In multivariate analysis, a more extensive node resection remained a significant prognostic factor for improved survival in intermediate/high-risk patients after adjusting for other factors including age, year of diagnosis, stage, grade, adjuvant radiotherapy, and the presence of positive nodes (P < .001). CONCLUSIONS: The findings of the current study suggest that the extent of lymph node resection improves the survival of women with intermediate/high-risk endometrioid uterine cancer.