Background: Socioeconomic deprivation has been described as a barrier to cancer clinical trial participation. However, few studies have examined socioeconomic deprivation using patient-level or granular geocoded designations. To overcome this challenge, the Area Deprivation Index (ADI) was used to assess neighborhood socioeconomic deprivation in a cohort of gastrointestinal cancer clinical trial patients at an NCI-Designated Comprehensive Cancer Center. Methods: Patients enrolled in a gastrointestinal cancer clinical trial from 2008 to 2019 with an identifiable ADI national rank were identified. Socioeconomic deprivation was assessed using the ADI, a publicly available, validated dataset that ranks census block groups into percentiles using variables such as income, education, employment, and housing characteristics. For this study, ADI was categorized as quintiles listed in the table. Statistical analyses included Chi-square and Kruskal-Wallis tests. Results: The median age of the cohort (N=1,334) was 62.0 years. Most patients were male (54.3%). Race included White (88.2%), African American (6.8%), and Asian (1.5%) patients. Hispanic/Latinx patients made up 6.7% of the cohort. The median ADI was 46. The proportion of enrollees from lowest to highest ADI quintile was 11.2%, 29.3%, 27.3%, 19.1%, and 13.1%. Trial enrollment differed by ADI and age (p=0.019), gender (p=0.042), race (p<0.001), and insurance (p=0.001). Conclusions: In this study, patients enrolled in gastrointestinal cancer clinical trials had lower neighborhood socioeconomic deprivation than the national or state average. African American, Hispanic/Latinx, female, and uninsured patients comprised a lower proportion of enrollees compared to catchment area estimates (10.6%, 17.7%, 51.3%, and 12.4%, respectively). These findings suggest inequity in clinical trial enrollment and warrant further studies to identify drivers of these disparities.