Abstract Introduction As a matter of course, there has been an under-representation of women in academic medicine, resulting in discriminatory distribution of research grants. This study examines the trend of funding allocation of R01 grants in Breast oncology by the National Institutes of Health with specific focus on the distribution of funding between gender. Methods The data were retrieved from the NIH RePORTER (Research Portfolio Online Reporting Tools Expenditure) using breast oncology-related search terms from 2018-2021. The gender was categorized using Genderize. The number of citations, publications, H-index, and seniority were obtained from Scopus and Web of Science in December 2022. Consumer Price Index was used to adjust funding amount to 2021 equivalent U.S. dollars. Linear regression was used for analysis. Results A total of 885 NIH-funded R01 grants amounting to $444.6 million were awarded for breast oncology research. Women (n=390; 44.1% [95% CI: 40.8%-47.3%]) received relatively fewer grants than men (n=495; 55.9% [95% CI: 52.7%-59.2%]). From 2018-2021, there was a significant increase in the number of grants awarded among both men (90 to 155, p<0.01) and women (71 to 115, p=0.036). Similarly, there was a significant increase in the grant amount (in millions) awarded among men (43.4 to 76.5, p<0.01) but not in women (36.7 to 56.1, p=0.11). Of the 212 co-PIs, 133 (62.7% [95% CI: 56.2%-69.2%]) were men and 76 (37.3% [95% CI: 30.8%-43.8%]) were women. There was no significant difference in h-index (48 vs 44, p=0.12), number of publications (158 vs 138, p=0.08), and citations (13272 vs 8092, p=0.06) between the male and female PIs. Funding amount was significantly associated with number of publications (β=0.35, p<0.01), seniority (β=0.25, p<0.01) and institution (p<0.01). Conclusion Our analysis shows continued gender disparity as only 44% of total R01 grants were awarded towards females for breast oncology between the fiscal years 2018 to 2021. Though the proportion of discrepancy is lower as compared to other malignancies. A collaborative effort is still needed to bridge the gap and advance gender equality. Citation Format: Janta Ukrani, Aruba Sohail, Sarah Khan, Ibrahim Zahid, Muhammad Zain Farooq, Michael Vishal Jaglal. Gender Disparities in the National Institutes of Health Funding for Breast Oncology [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A090.