To evaluate the prognostic impact of aortic vs. pelvic lymph node (LN) metastasis among women with endometrial cancer (EC). Using data from the SEER 18 Registries we identified 3650 women with LN positive (stage IIIC) EC. We used Kaplan-Meier curves and log-rank tests to compare mortality between women with stage IIIC1 and IIIC2 disease. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between stage III sub-stage (IIIC1 vs. IIIC2) and survival. Endometrioid tumors were more common among women with stage IIIC1 than IIIC2 tumors (62.5% vs. 54.3%) while, non-endometrioid histologies were more common among stage IIIC2. In the multivariable model, stage IIIC2 was associated with higher all-cause (HR = 1.44, 95% CI = 1.22–1.69) and EC-specific mortality (HR = 1.49, 95% CI = 1.25–1.77) compared with IIIC1. Women with non-endometrioid EC had poor survival, in particular, women with carcinosarcomas had higher EC-specific mortality compared to women with endometrioid EC (HR = 3.32, 95% CI = 2.71–4.07). When stratifying women according to substage, older age and non-endometrioid histology were associated with higher EC-specific mortality. Compared to women with a pelvic-only LN dissection, women with pelvic and aortic dissections had lower all-cause (HR = 0.74, 95% CI = 0.63–0.88) and EC-specific (HR = 0.79, 95% CI = 0.66–0.95) mortality. Women with aortic LN positive EC are more likely to die from their disease. Older women and non-endometrioid histologies are more likely to have aortic LN involvement. Compared to women with a pelvic-only LN dissection, women with pelvic and aortic dissections had lower EC mortality. •Endometrial cancer with aortic lymph node metastasis portends a worse outcome.•Older age and non-endometrioid histology are independent poor prognostic indicators in lymph node positive EC.•Carcinosarcoma histology has the worse outcomes in lymph node positive EC.•Compared to women with a pelvic-only LN dissection, women with pelvic and aortic dissections had lower EC mortality.