Abstract Background. Endometrial cancer (EC) is the most common gynecologic malignancy in the US, with an increasing incidence. Non-Hispanic Black (NHB) women are disproportionately impacted by EC but the complex mechanisms by which this is occurring are not yet fully understood. Taking a social ecological approach to this issue, our objective was to determine if there are associations between county-level OB-GYN provider density and residential segregation as measured by the Index of Concentration at the Extremes (ICE) on late-stage EC diagnoses in Florida. Methods. All malignant EC cases were identified from 2001 to 2016 in the Florida Cancer Database System (FCDS). Using 5-year estimates from the 2013-2017 American Community Survey, five county-level ICE variables were calculated: economic (high vs low), race and/or ethnicity (non-Hispanic white (NHW) vs. NHB and NHW vs. Hispanic), and racialized economic segregation (low-income NHB vs. high-income NHW and low-income Hispanic vs. high-income NHW). County-level provider density was calculated as the number of OB-GYN providers divided by the female population of each county multiplied by 100,000. Early stage was defined as local and late stage was defined as regional/distant. Multivariable-adjusted logistic regression models were specified to estimate the association between each ICE variable and provider density separately on late-stage diagnosis of EC. Results. There were a total of 50,363 EC cases in Florida from 2001 to 2016 with 44,678 (88.7%) having stage information. Of those with stage information, the mean age at diagnosis was 64.1 years (SD: 11.9), 71.8% were NHW, 11.5% were NHB, 14.0% were Hispanic, and 2.8% were other race. The majority of individuals had government insurance (50.6%). More NHB women (27.1%) were diagnosed with aggressive EC histologies relative to NHW (16.4%) and Hispanic women (15.5%) (p<0.001). 14,366 (32.2%) were diagnosed with late-stage EC. A larger proportion of NHB women were diagnosed with later-stage EC compared to NHW women and Hispanic women (43.7% vs. 30.3% and 32.4%, respectively, p<0.001). NHB and Hispanic women had significantly greater odds of being diagnosed with later-stage EC compared to NHW women, regardless of residential segregation (OR: 1.46, 95% CI: 1.36, 1.56 and OR: 1.09, 95% CI: 1.01, 1.17, respectively). Women living in more economically disadvantaged Hispanic segregated counties had a greater odds of being diagnosed with later-stage EC compared to those living in more NHW segregated areas (OR: 1.16, 95% CI: 1.00, 1.65). Provider density was not found to be associated with later-stage diagnosis. Discussion. Advanced stage EC at diagnosis among Black and Hispanic women in Florida seems to be largely independent of provider density and residential segregation, though NHB more commonly present with metastatic disease. Biologic drivers of oncogenesis and barriers to timely care in this group require further exploration. Given the diversity and representation from Afro-Caribbeans in Florida, community-level investigations are required. Citation Format: Ashly Westrick, Zinzi Bailey, Matthew Schlumbrecht. Influence of residential segregation and women’s health provider density on advanced stage endometrial cancer diagnoses [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr B076.