Abstract Background: ASCO has reaffirmed critical role of early phase (EP) clinical trials (CT) in cancer research and treatment that patients (pts) may achieve improvement in quality of life, experience psychological and direct medical benefits. Disparities in access and participation to CT exist and are more profoundly seen in EP CT with challenge of engaging underrepresented populations (UP) in EP CT which are often complex and only available at larger cancer centers in metropolitan areas. NCI’s Create Access to Targeted Cancer Therapy for Underserved Populations (CATCH-UP.2020) helped bring EP CT to UP. To determine the impact of financial toxicity (FT) as a barrier specific to EP CT participation of UP, the validated COST-FACIT tool was used to survey cancer pts undergoing treatment at the University of Kansas Cancer Center. Methods: This study was approved by our Institutional Review Board (Study 00150640). During routine scheduled visits, pts completed COST-FACIT survey on touch screen tablet. A list of validated questions on EP CT awareness, access, and willingness to participate were included in the survey. Pts responded to 12-item COST-FACIT questionnaire describing the relationship between financial stress and treatments (scale 0 to 4). The score was computed using responses captured from COST-FACIT. Based on literature, scores <26 were determined to be higher FT. Two-sided Fisher's Exact Tests were used to test for a significant association at an alpha level of 0.05. UP included racial and ethnic minorities, low socioeconomic status, low education, and rural. Results: Of 108 pts, 101 completed surveys. 45% identified as female and 55% as male. 11.2% 18–35 years (yrs) of age, 13.9% 36 –50 yrs, 24% 51–65 yrs and 54% >65 yrs. 62.4% were white, 17.8% black, and 19.8% others (Asian or Native American). 8.9% completed <12th grade, 23.8% completed high school, 29.7% have some college experience, 22% completed college and 16% have master’s/doctoral degree. COST-FACIT mean score was 25.7 (SD 10.4, r^2 of 0.48) showing significant financial stress. 46% of pts had scores <26. Pts 18-35 yrs (p=0.02), 36–65 yrs (p=0.00), had yearly incomes of >150,000 (p=0.02) or unaware of their yearly income (p=0.05) were more likely to have significant FT. Pts with < 12th grade (14.89%) or some college experiences (34.09%) were likely to have significant FT. Pts identifying as Asian or Native American were more likely to experience FT than white or black. Conclusion: Almost half of our pts suffer from significant FT creating disparities in EP CT access and participation. Data suggest ages 35-65 yrs, low levels of education, and races other than white and black experience higher levels of FT that is a barrier to EP CT participation. These data support our ongoing efforts to bring innovative EP CT to everyone including the VA and our other outreach partners with higher concentrations of UP. Data on rural and health professional shortage areas will be reported during the meeting. This project was supported in part by The University of Kansas Cancer Center P30CA168524. Citation Format: Kamiyah Hicks, Anusha Chidharla, Dinesh Pal Mudaranthakam, Hope Krebil, Issa Espinoza, Asuka Suzuki, Sam Pepper, Angelica Allen, Jill Hamilton - Reeves, Debra Sullivan, Anna Arthur, Saqib Abbasi, Anup Kasi, Rahul Parikh, Elizabeth Wulff - Burchfield, Al - Ola Abdallah, Lori Barbosa, Erin Carroll, Jennifer Heins, Tara Lin, Gary Doolittle, Weijing Sun, Joaquina Baranda. The impact of financial toxicity as a barrier to access and participation in early phase clinical trials for underrepresented populations using the COST–FACIT tool [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 B142.