Abstract Introduction: The COVID-19 pandemic has altered the health care delivery system. The purpose of this study was to determine the impact of the COVID-19 pandemic on breast cancer screening, diagnosis, and treatment. Methods: Potential survey respondents were identified through partnerships with breast cancer organizations including Dr. Susan Love Foundation for Breast Cancer Research, SHARE, Survivingbreastcancer.org, Sisters Network Inc., the African American Breast Cancer Alliance, and through ResearchMatch.org. Study information was shared via social media, websites, or email. Individuals were eligible for this study if they: 1) receive routine breast cancer screening, or 2) are undergoing diagnostic evaluation for breast cancer, or 3) had ever been diagnosed with breast cancer. Participants accessed and completed the 10-15-minute REDCap survey either by emailing the research team and receiving a private survey link or by clicking a public link. The survey collected information on respondent demographics; breast cancer screening and diagnosis; the extent to which screening, diagnosis, or treatment had been changed, delayed, or canceled because of COVID-19; personal protective practices; extent of worry about financial and health implications of COVID-19; and use of telemedicine. We used descriptive statistical analyses to better understand the impact of the COVID-19 pandemic on respondents. Results: There are currently 415 survey respondents, 404 of whom agreed to participate in the study. 46.8% (N=189) of respondents were white, 26.7% (N=108) Black, 6.7% (N=27) Asian, and 5.5% Hispanic or Latino (N=22). Most respondents were between the ages of 50 and 69 years (52.2%, N=211). 43.3% (N=175) of respondents had been diagnosed with breast cancer and, of those, 36% (N=63) were in active treatment. More than a quarter of participants (26.5%, N=107) reported delayed or canceled breast cancer care due to COVID-19; the most frequently affected care was screening mammogram, ultrasound, or MRI (97.2%, N=104). 20.6% (N=13) of women in active treatment reported delayed or canceled surgery, chemotherapy, or radiation visits. 22.3% (N=90) of respondents reported that an in-person visit was changed to a phone call or videoconference, and 39.1% (N=158) said they had discussed COVID-19 with a health care provider. 29.1% (N=51) of those with breast cancer were worried or very worried that the COVID-19 pandemic would make it harder for them to get cancer care; among those without breast cancer, 34.9% (N=80) were worried that COVID-19 would make it harder to obtain health care, including breast cancer screening and diagnosis. Conclusions: The COVID-19 pandemic continues to disrupt breast cancer-related care, primarily screening. Planning and coordination are necessary to ensure the timely return of these patients to care. Most participants agreed to be contacted for follow-up, allowing us to investigate the long-term effects of delayed breast cancer screening, diagnostic evaluation, and treatment on health outcomes. Citation Format: Erica T. Warner, Emily Restrepo, Christine Benjamin, Ricki Fairley, Laura Roudebush, Leah Eshraghi, Crystal Hertz, Simo Du, Laura Carfang. Patient-reported impact of the COVID-19 pandemic on breast cancer screening, diagnosis, and treatment: A national survey [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2020 Jul 20-22. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(18_Suppl):Abstract nr S11-02.