Background/Aims@#Colorectal adenomas are precancerous lesions that may lead to colorectal cancer. Recent studies have shown that colorectal adenomas are associated with atherosclerosis. The cardio-ankle vascular index (CAVI) and ankle-brachial index (ABI) are noninvasive methods for evaluating atherosclerosis. This study examined the association between atherosclerosis and high-risk colorectal adenomas based on the CAVI and ABI. @*Methods@#The data of patients aged ≥50 years who had a colonoscopy and CAVI and ABI measurements from August 2015 to December 2021 at the Kangwon National University Hospital were analyzed retrospectively. After the colonoscopy, subjects were divided into no, overall, and high-risk (size ≥1 cm, high-grade dysplasia or villous adenoma, three or more adenomas) adenoma groups based on the pathology findings. The data were subjected to univariate and multivariate logistic regression analyses. @*Results@#Among the 1,164 subjects, adenomas and high-risk adenomas were found in 613 (52.6%) and 118 (10.1%) patients, respectively. The rate of positive ABI (<0.9) and positive CAVI (≥9.0) were significantly higher in the high-risk adenoma group (22.0% and 55.9%) than in the no adenoma (12.3% and 39.6%) and the overall adenoma group (15.7% and 44.0%) (p=0.008 and p=0.006, respectively). Multivariate analysis revealed a positive CAVI and smoking status to be significantly associated with high-risk adenoma with an odds ratio of 1.595 (95% confidence interval 1.055–2.410, p=0.027) and 1.579 (1.072–2.324, p=0.021), respectively. @*Conclusions@#In this study, a significant correlation between positive CAVI and high-risk adenomas was observed. Therefore, CAVI may be a significant predictor for high-risk colorectal adenoma.