Abstract Introduction: Cancer family history is a risk factor for multiple cancer types. Knowing and sharing cancer family history can help inform cancer screening and genetic testing which ultimately aids in cancer prevention and early detection. There is limited knowledge about how people with cancer family history appraise their own risk of developing cancer which may influence screening and preventive behaviors, particularly among marginalized populations like Black adults. The objective of this study was to conduct a community-engaged survey to assess the relationship between self-reported cancer family history and perceived risk of developing cancer among Black adults. Methods: Using community-based recruitment methods in partnership with national Black-led organizations we conducted an online survey on cancer family history in Black communities. Individuals could participate if they self-identified as Black or African-American, were 18 or older, resided in the US, and could complete a survey in English. In the survey, participants were asked if members of their immediate families had ever been diagnosed with cancer, and if so which family members. Participant responses were categorized into: No family history, 1 family member with cancer history, 2+ family members with cancer history. Participants without a personal history of cancer were asked “On a scale of 0 to 100, what do you think your chances are of getting cancer? (0 = no chance of getting cancer and 100 = you will definitely get cancer)”, and to rate their level of agreement with the following statement “I feel I will get cancer sometime during my life.” Chi-squared and Kruskal-Wallis tests were used to assess the relationship between the number of family members with cancer and self-perceived cancer risk. Results: Overall, 100 participants from 17 states responded to the survey. Among participants, 93% were women, 84% had a bachelor’s degree or higher, and 16% reported a personal history of cancer. In total, 20% (n=20) reported no cancer family history, 30% (n=30) reported 1 family member with cancer, and 50% (n=50) reported 2 or more relatives with cancer. The mean perceived chance of developing cancer was 41.3% (95% CI: 33.6, 49.0) among people with no family history of cancer, 29.0% (95% CI: 22.2%, 35.6%) among people with one relative with cancer, and 48.2% (95% CI: 42.1, 54.2) among people with multiple relatives with a cancer history (p=0.0002). In addition, 17.6% of people with no family history, 0% with 1 relative family history, and 16.7% with 2 or more relative cancer family history somewhat or strongly agreed to the statement , “I feel I will get cancer sometime during my life,” (p=0.001). Conclusion: In this community-partnered survey of a diverse Black US adults, there was an association between number of family members with a cancer history and self-perceived risk of developing cancer. Understanding the appraisal of perceived cancer risk by level of cancer family history in Black adults could help inform targeted cancer prevention and early detection interventions. Citation Format: Mya L. Roberson, Laura Crandon, Jordyn A. Brown, Jordan Speller, Monique Gary. Assessing the relationship between family history of cancer and self-perceived cancer risk among Black adults in the United States [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr B090.