6500 Background: Racial/ethnic minorities have disproportionately increased risk of contracting COVID-19 and experiencing severe illness; they also have worse breast cancer (BC) outcomes. COVID-19 outcomes among racial/ethnic minorities with BC are currently unknown. We sought to compare clinicopathologic characteristics and COVID-19 outcomes stratified by race/ethnicity. Methods: The COVID-19 and Cancer Consortium registry (NCT04354701) was used to identify patients with invasive BC and laboratory-confirmed SARS-CoV-2 diagnosed in the U.S. between 2020-03-06 and 2021-02-04. The primary analysis was restricted to women who self-identified as non-Hispanic White (NHW), non-Hispanic Black (NHB), or Hispanic (H). Demographic, cancer characteristics, and COVID-19 outcomes were evaluated. COVID-19 outcomes included: hospital admission, intensive care unit (ICU) admission, mechanical ventilation, death within 30 days of COVID-19 diagnosis and death from any cause during follow-up. Descriptive statistics were used to compare clinicopathologic characteristics and Fisher exact tests were used to compare COVID-19 outcomes across the 3 racial/ethnic groups. Results: A total of 1133 patients were identified of which 1111 (98%) were women; of which 575 (52%) NHW, 243 (22%) NHB, 183 (16%) H, and 110 (10%) other/unknown. Baseline characteristics differed among racial/ethnic groups. H were younger (median age: NHW 63y; NHB 62y; H 54y) and more likely to be never smokers (NHW 62%; NHB 62%; H 78%). NHB had higher rates of obesity (NHW 40%; NHB 54%; H 46%), diabetes (NHW 16 %; NHB 32%; H 20%) and combined moderate and severe baseline COVID-19 at presentation (NHW 28%; NHB 42%; H 28%). Cancer characteristics are as shown (Table). Significant differences were observed in outcomes across racial/ethnic groups including higher rates of hospital admission (NHW 34%; NHB 49%; H 34%; P <0.001), mechanical ventilation (NHW 3%; NHB 9%; H 5%; P=0.002), 30-day mortality (NHW 6%; NHB 9%; H 4%; P=0.043) and total mortality (NHW 8%; NHB 12%; H 5%; P=0.05) among NHB compared to NHW and H. Conclusions: This is the largest study to show significant differences in COVID-19 outcomes by racial/ethnic groups of women with BC. The adverse outcomes in NHB could be due to higher moderate to severe COVID-19 at presentation and preexisting co-morbidities. H did not have worse outcomes despite having more active disease and recent anti-cancer therapy, including with cytotoxic chemotherapy – potentially due to younger age and nonsmoking status.[Table: see text]