Background Cardio-ankle vascular index (CAVI) is a marker that reflects the overall stiffness of the aorta, femoral artery, and tibial artery. Several previous reports have shown the usefulness of CAVI for coronary artery disease (CAD) presence and severity. According to coronary angiography (CAG) and intracoronary imaging such as optical coherence tomography (OCT), coronary plaque burden and morphology as predictors of all-cause and cardiovascular mortality were previously evaluated. The aim of our study was to assess the correlation between CAVI value and Gensini's score for the coronary plaque burden as well as CAVI value and plaque morphology by using OCT. Methods A total of 548 consecutive patients who underwent CAG were enrolled in this study. CAVI value was evaluated in all patients, and OCT was performed in 89 of the 548 patients. CAVI ratio is calculated as CAVI/CAVIex (expected normal value of CAVI, which is calculated using patient age and sex). Results On multivariable analysis, sex, age, hypertension, diabetes mellitus, and CAVI were significantly correlated with logarithmized Gensini's score. CAVI values were significantly higher in the groups with CAD, which were 1 vessel disease (VD), 2VD, and 3VD, than in the OVD group (p<0.001). However, there was no statistical significance between CAVI ratio and OCT findings in terms of plaque morphology. Conclusions CAVI might be useful as a routine test for the detection of CAD and the evaluation of atherosclerotic plaque burden but not coronary plaque vulnerability.