Aims Carotid intima-media thickness (CIMT) has been widely used to risk stratify and predict coronary artery disease (CAD) despite its significant limitations. To test whether radial artery intima thickness (RIT) is closely associated with atherosclerotic risk factors, and whether RIT has an independent and additive value for diagnosis of CAD. Methods and results One hundred and sixteen consecutive CAD patients and 79 age and gender-matched healthy controls were enrolled in this study. RIT, radial media thickness, radial intima-media thickness, and CIMT were measured with a high-resolution ultrasound biomicroscopy. Binary logistic regression was used to assess association between CAD and ultrasonic parameters, biochemical biomarkers or traditional risk factors. Receiver-operating characteristic curves were plotted to compare performances of several diagnostic models. RIT was positively associated with age, systolic blood pressure, statin administration, and hypertension. The independent value of RIT for differentiating CAD was similar to that of CIMT, but the add-on value of RIT to traditional risk factors for detecting CAD was superior to that of CIMT. Moreover, addition of RIT and CIMT to traditional risk factors increased AUC for detecting CAD from 0.724 to 0.867 significantly (P = 0.003). Conclusion RIT could detect CAD independently similarly to CIMT. The add-on value of RIT to traditional risk factors for detecting CAD was superior to CIMT and addition of RIT and CIMT to traditional risk factors markedly increased the power to diagnose CAD. Thus, RIT measured by ultrasound biomicroscopy provided a novel approach to noninvasive diagnosis of CAD.