5000 Background: To determine the potential benefit of lymphadenectomy (LNX) during surgical staging procedure in women with early and advanced endometrioid uterine cancers. Methods: Demographic and clinico-pathologic information were obtained from the Surveillance, Epidemiology and End Results program from 1988 to 2001. Data were analyzed by using Kaplan-Meier methods and Cox proportional hazards regression. Results: Of 39,396 women (median age: 65; range 19–102) with endometrioid uterine cancers, 12,333 (31.3%) underwent a surgical staging procedure with LNX. The remainder received a hysterectomy and bilateral salpingo-oophorectomy only. 34,871 (88.5%) were Caucasian, 1,742 (4.4%) were African-American, 1,841 (4.7%) were Asian and 942 (2.4%) were other. The 5-year disease-specific survivals (DSS) were 93.3%, 85.4%, 69.3%, and 38.3% in patients with FIGO stage I-IV diseases, respectively. The 5-year DSS of stage I-IV women who underwent LNX were 95.5%, 90.4%, 73.0%, and 53.3% compared to 96.6%, 82.3%, 61.2%, and 28.2% in those without LNX. Those with stage II (p < 0.001), III (p < 0.001), and IV (p < 0.001) diseases after LNX had significantly better survival; however, the benefit of LNX was not demonstrated in stage I disease. The proportion of stage I patients with grade I histology or tumors limited to the endometrium was significantly higher in those who did not receive LNX compared to those who did (54.8% vs. 34.7%; p < 0.001 for grade I disease; 26.6% vs. 15.9%; p < 0.001 for non-myometrial invasion). In stage I grade 3 endometrioid uterine cancer, patients with LNX had a better 5-year DSS than those without LNX (90.0% vs. 84.97%; p = 0.0001); however, these findings were not seen in grade I (p = 0.26) and grade II (p = 0.14) diseases. In the subset of patients with stage IC grade 3 disease, there was a trend toward an improvement in survival associated with LNX (81.7% vs. 76.5%; p = 0.07). In the overall study group, younger age, African-American race, advanced stage disease, grade 3 histology, and lymphadenectomy. Conclusions: Our data suggest that lymphadenectomy improves the survival of women with stage I grade 3, stage II-IV endometrioid uterine cancers. No significant financial relationships to disclose.