Abstract Purpose: Thirty years after the NIH Revitalization Act, racial/ethnic minority (REM) patients continue to be underrepresented in oncology clinical trials with disproportionately low rates of participation compared to non-Hispanic whites. Health system, patient, and medical provider factors contribute to this disparity. However, little is known about clinical trial investigator perspectives of REM participation in oncology clinical trials and their contribution to this disparity. To our knowledge there are no published quantitative studies that have investigated this important and actionable topic. Methods: We conducted a cross-sectional, anonymous, pilot survey of medical, radiation, and surgical oncology clinical trial investigators at a large academic center. Over a 5-week period, 107 individuals received a survey. The survey assessed 6 domains regarding disparities in REM participation in clinical trials: investigator knowledge, attitudes, and prior training on the topic, self-efficacy and motivation for improvement in addressing known disparities, and perceived barriers to REM participation in clinical trials. Modified, previously validated items were used when possible. Results: Of 60 respondents (56% response rate), 33 were male (55%). Thirty-six identified as non-Hispanic white (60%), 16 as Asian (27%), 1 as Hispanic/Latinx (2%), and 7 as other/prefer not to state (11%). Respondents included 49 medical (82%), 7 surgical (11%), and 4 radiation oncologists (7%). Average time as a clinical trial investigator was 14 years (2-40). Respondents opened an average of 2 clinical trials as primary investigator in the past year (0-10). A majority (83%) strongly agreed disparities exist in REM clinical trial participation and that the resulting lack of diversity is problematic (75%). However, only 34% strongly agreed they consider ways to achieve racial/ethnic diversity among trial participants when designing clinical trials, or ways to specifically enroll REM patients (28%). Respondents most commonly cited patient rather than health system factors as barriers to REM participation in clinical trials. Notably, nearly half (45%) agreed that lack of REM participation is a problem they cannot directly address. A majority (83%) endorsed wanting to improve their consideration of barriers to REM participation as they design clinical trials and wanted help to improve (86%). Conclusion: Our results suggest there is awareness among clinical trial investigators at our academic center of disparities in REM participation in oncology clinical trials and the problem this poses to cancer care. There is also a pervasive view that primary barriers to REM participation are patient factors, and investigators do not feel they can directly address these. Nonetheless, there is motivation among investigators to improve in their ability to consider barriers to REM participation as they design clinical trials. Interventions that improve investigators’ self-efficacy for addressing barriers to REM participation in clinical trials, especially patient level barriers, are needed. Citation Format: Natalie P. Bransky, Anne M. Walling, John A. Glaspy, Maria Garcia-Jimenez. Exploring the unexplored: Clinical trial investigator perspectives of disparities in racial/ethnic minority participation in oncology clinical trials [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr A078.