Background and Objectives: Indices of aortic wave reflections like augmentation index (AIx) have been shown to assess coronary artery disease (CAD) and cardiovascular risk in several studies. In recent studies, AIx are known to be correlated well with vascular aging in the relatively younger population. The aim of the study was to assess the relation between non-invasively measured indices of aortic pulse wave reflections and the severity of CAD in different age groups. Subjects and Methods: The study group consisted of 80 patients (40 of aged <65 years, 40 of aged >65 years) who admitted to our institute for elective coronary angiography from March 2010 to June 2010. We non-invasively measured indices of aortic wave reflections including augmentation pressure (AP), AIx and AIx corrected for heart rate of 75 b.p.m. (AIx@75) using radial pulse tonometry (SphygmoCor짰) and calculated pulse pressure (PP) amplification defined as the ratio between brachial PP and aortic PP. Significant CAD was defined as having ���50% stenosis of at least one of its segments or prior coronary revascularization. The extent of CAD was defined according to the number of coronary vessels with ���50% stenosis. The severity of CAD was assessed by Gensini score. Results: For baseline characteristics, there was no significant difference in gender, smoking, hypertension, diabetes, body mass index, the history of myocardial infarction, cholesterol, creatinine and Gensini score between patients of aged <65 years and >65 years. In univariate analysis, higher central AP, AIx, AIx@75 and lower PP amplification were significantly correlated with Gensini score in patients aged <65 years, but not correlated in patients aged >65 years. In multivariate analysis, after controlling age, gender, smoking, hypertension, diabetes, body mass index, the history of myocardial infarction, cholesterol and creatinine, the correlation was significant as the univariate analysis. Conclusion: Non-invasively measured indices of increased aortic wave reflections were correlated with severity of CAD in younger patients up to 65 years of age. Large elastic artery stiffening thus can be considered as a useful non-invasive marker of the severity of coronary artery disease (CAD) in younger patients.