Arterial stiffness is known to be an important surrogate marker for atherosclerosis and predictor of peripheral vascular and cardiovascular (CV) disease. Whether high cardio-ankle vascular index (CAVI) is associated with the development of rapid glomerular filtration rate (GFR) decline remains uncertain. The study aimed to determine the relationship between CAVI and renal function progression among patients with high CV risk. Methods: This study employed a prospective cohort design with 1-year follow-up among patients with high CV risk. Arterial stiffness was measured using CAVI method. GFR was estimated using the chronic kidney disease (CKD) epidemiology collaboration equation, and rapid decline in GFR was defined with decrease in GFR ≥ 5 mL/min/1.73 m 2 yearly. Results: Of 352 patients with mean age 67.8 10.1 years, 224 patients (63.6%) were suspected to have arteriosclerosis (CAVI ≥ 9), and 208 patients (59.1%) had CKD (GFR 60 mL/min/1.73 m 2). Annual decline of GFR was −0.75 [interquartile range (IQR), −1.16 to 6.08] mL/min/1.73 m 2 /year, and 30.1% of patients experienced a rapid decline in GFR. Compared with normal CAVI (CAVI 8), high CAVI (CAVI ≥ 9) and borderline CAVI (CAVI 8-8.9) in all subjects and subgroup of baseline GFR 60 mL/min/1.73 m 2 were associated with rapid GFR decline. Multivariable analysis showed that high CAVI and borderline CAVI were associated with 2.47-fold (95% CI, 0.89-6.84; P 0.082) and 4.04-fold (95% CI, 1.46-11.18; P 0.007) increased odds ratio of rapid GFR decline, respectively. Conclusion: Among patients with high risk of CV with or without CKD, high CAVI (cut point of ≥ 9) was independently associated with a rapid decline in GFR, suggesting that systemic vascular stiffness predicted a decrease in renal function in this population. ness of vessels potentially leads to microvascular ischemia and tissue damage including renal microvascular supply 6). Arterial stiffening causes increased systolic blood pressure and pulse pressure. Both factors might be associated with rapid decline in glomerular filtration rate (GFR) 7). Related clinical studies have indicated an independent association between arterial stiffness and decline in renal function, but the results were inconsistent, differing in study populations, environments, and confounding factors 8-11). The association between arterial stiffness and renal progression remains to be established. Cardio-ankle vascular index (CAVI) Copyright©2019 Japan Atherosclerosis Society This article is distributed under the terms of the latest version of CC BY-NC-SA defined by the Creative Commons Attribution License.