Abstract INTRODUCTION Participating in a clinical trial is a personal choice and an individual experience. Several barriers to recruitment of high risk men and women in chemoprevention trials have been documented; however, to our knowledge, there are no existing reports on participant satisfaction in such trials. Therefore, our aim was to describe and evaluate participants’ perception of their experience with participating in chemoprevention trials conducted by CPN by summarizing the 5-item “Was It Worth It” (WIWI) tool for each trial and across the trials, and according to race/ethnicity, sex, age, site, and organ of primary interest. METHODS Because participants who participate in chemoprevention trials tend to be at increased cancer-risk, but otherwise healthy, the WIWI tool can help answer simple questions about participants’ assessment of whether or not participation in such a trial was worthwhile. The WIWI tool was consistently administered at the end of the intervention period in each trial conducted by CPN; since 2003, 7 trials have completed the study intervention period and are included in the results reported here. RESULTS The scientific focus of the 7 trials targeted 5 organs: breast, colorectum, esophageal, hepatobiliary, and lung. Of the 485 participants registered to these 7 trials, 419 (86.4%) were non-Hispanic white, 19 (3.9%) non-Hispanic black, 32 (6.6%) Hispanic, 14 (2.9%) other race/ethnicity, and 1 (0.2%) unknown race/ethnicity; there were 120 (24.7%) females. In total, 446 (92.0%) participants completed the WIWI questionnaire at the end of their respective intervention period. Across the trials, 93% [95% CI] [90.6%, 95.4%] of the participants indicated that participation was worthwhile and 92% [89.5%, 94.5%] reported that they would participate again. Additionally, 414 (92.8%) participants indicated that they would recommend participating in the current research study to others, while 10 (2.3%) indicated that they would not and 22 (4.9%) were uncertain. Furthermore, several participants provided actionable feedback to the question “If there was one thing that could have been done to improve your experience in this research study, what would it be?” Participant feedback on overall changes in quality of life and on their expectations with participation in the trial was positive but more nuanced, varying according to trial and participant composition. CONCLUSION In this dataset of chemoprevention trial participants enrolled through the CPN consortium, highly favorable feedback was evident with respect to the overall study experience, suggesting that the recruitment and retention methods employed are facilitating success. These data can be used to help advance the NCI accrual quality improvement program in developing/enhancing strategies to improve accrual, retention, and adherence as well as enhance participant diversity in subsequent trials. Citation Format: David Zahrieh, Ryan P. McMurray, Nathan R. Foster, Paul J. Limburg, Sumithra J. Mandrekar. Participant satisfaction with cancer chemoprevention clinical trials: The Mayo Clinic Cancer Prevention Network (CPN) experience [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5092.