We aimed to examine the association between the maximum intima-media thickness of the carotid artery (Max IMT) and renal prognosis, considering their potential interaction with age. Methods: Survival analyses were performed in 112 patients with chronic kidney disease (CKD), to assess renal prognosis, with the endpoint defined as a ≥ 30% decline in estimated glomerular filtration rate (eGFR) or endstage renal disease. Results: During a median follow-up of 12.5 years, 44 participants reached the study endpoint. The major determinant of Max IMT was the maximum IMT of the internal carotid artery (Max ICA-IMT), which was the distribution ratio of 50.0% of Max IMT. Kaplan-Meier analyses showed that Max IMT ≥ 1.5 mm was significantly associated with renal prognosis when age and eGFR were matched. On multivariate Cox regression analysis, Max IMT was significantly associated with the renal outcomes and had a significant interaction with the age categories (≥ 65 years or 65 years) (P 0.0153 for interaction). A 1-mm increase in Max IMT was significantly associated with disease progression in the sub-cohort 65 years age-category, but not in the ≥ 65 years age-category; similarly the hazard ratio (HR) in the 65 years age-category was higher than in the ≥ 65 years age-category (HR: 2.52 vs. 0.95). Comparable results were obtained for Max ICA-IMT, Max bulb-IMT, but not for Max common carotid artery-IMT. Conclusions: A higher Max IMT was a significant renal prognosis factor in patients with CKD aged 65 years. Our results may provide new insights into treating CKD. value to the Framingham risk score. In a Japanese study of 1,358 men aged 60 to 74 years 2) , those with Max IMT ≥ 1.5 mm had a 3-fold higher risk of stroke than those with Max IMT 1.5 mm. Furthermore, among patients with coronary artery disease with a maximum IMT of the common carotid artery (Max CCA-IMT) ≥ 1.1 mm, progression of the Max CCA-IMT was associated with future coronary events 4). Recently, Polak et al. 6) made the assertion that ICA-IMT and CCA-IMT represent different phenotypes, Copyright©2020 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.