Background: As multinational trials are increasing, standardization of IRB review has become increasingly important. Though inconsistency is often inevitable due to varying opinions on ethics, standardization and understanding the differences are required to ensure IRB review quality. Thus, we aimed to develop and suggest a quality assessment measure of IRB named “blind review” by reviewing the same research protocols by multiple IRB panels. We further describe an analysis of differences to understand the mechanism of IRB standardization. Methods: Based on the HRPP (Human research Protection Program) SOPs (Standard of Procedure), eight blind review results from January 2010 to December 2018, at a single institution with multiple panels, were included using the Severance Hospital HRPP database. Review results were analyzed with review scores ranging from 0 to 60 points, including good clinical practice (GCP) requirements and protocol issues. Panel agreement was estimated by observed multiple rater agreement. Differences between review scores according to member expertise and IRB member duration were analyzed with the Wilcoxon rank-sum test and Kruskal-Wallis test. Results: Observed multiple raters’ agreement increased from 0.444 (95% CI: 0.167-1.000) in 2010 to 0.479 (95% CI: 0.271-0.708) in 2014~2018 as IRB review experiences increased. In order to analyze the review mechanism, three GCP requirements and three protocol issues were scored (range 0 to 60). Mean values for GCP requirements and protocol issues were 19.25±8.21 and 18.40±9.04, respectively. Mean score of the panels where experts participated (n=16, 28.13±10.47) was higher than the control group (n=32, 25.16±10.96) (p=0.93). According to IRB members’ experience, scores for the group whose career spanned less than 3 years was 25.0±10.0 (n=14), those whose career spanned 3-5 years was 26.3±9.6 (n=23), and those whose career spanned more than 5 years was 27.3±14.2 (n=11). These results were statistically significant (p=0.09). Conclusions: We suggest blind review as an effective measure for overseeing and ensuring IRB review quality and overall GCP compliance.