Background: To examine surgical outcomes, patterns of adjuvant therapy, and survival for non-Hispanic Black (NHB) women compared to non-Hispanic White (NHW) and Hispanic (HS) women who have undergone surgery for high grade endometrial cancer in the Medicare population. Methods: We utilized the SEER-Medicare linked database to identify women who underwent surgery as a primary treatment for uterine grade 3 endometrioid adenocarcinoma, carcinosarcoma, clear cell carcinoma, or serous carcinoma between the years 2000 and 2015. Multinomial logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for receiving a treatment delay or not receiving adjuvant treatment (compared to those who received adjuvant treatment within 12 weeks) adjusted for clinical and demographic characteristics. Overall survival (OS) stratified by race/ethnicity, route of surgery, operative complications, and type and timing of adjuvant therapy were analyzed using the Kaplan-Meier method. Cox Proportional hazards regression was used to estimate hazard of death by race/ethnicity adjusted for known predictors, as well as surgical outcomes and adjuvant therapy patterns. Results: 12, 201 women met study inclusion criteria. NHB patients had a significantly worse five-year overall survival (OS) than HS and NHW patients (30.9 months vs 51.0 months vs 53.6 months, respectively). Approximately 8.6% of patients who received adjuvant treatment experienced a treatment delay (632/7, 282). Delay in treatment of greater than or equal to 12 weeks was significantly different by race/ethnicity (p=0.034), with 12% of HS, 9% of NHB, and 8% of NHW women experiencing a delay. After adjustment for number of complications, age, histology (endometrioid v. non-endometroid), FIGO stage, marital status, comorbidity count, surgical approach, lymph node dissection, and urban-rural code, HS had a 71% increased risk of treatment delay (OR 1.71, CI 1.23-2.38) for all stages of disease. In the same model, NHB race was independently predictive of decreased use of adjuvant treatment for FIGO stage II and higher (OR 1.32, CI 1.04-1.68). NHB race, number of perioperative complications, and non-endometrioid histology were predictive of worse OS in univariate models. Treatment delay was not independently predictive of worse 1- or 5-year survival at any stage. Conclusions: NHB race is predictive of worse 5-year survival across all stages and is also associated with omission of adjuvant treatment in ≥FIGO Stage II high grade endometrial cancers. HS ethnicity was associated with treatment delay across all stages. In unadjusted analyses, patients who experience treatment omission or delay experienced poorer OS, but these factors were not independently associated in multivariate analyses.