Background and Objectives: A prolonged heart rate-corrected QT interval (QTc) is known to be related to an increased risk of coronary artery disease (CAD) and suden cardiac death, while the carotid intima-media thick-ness (IMT) is related to CAD. We sought to evaluate the relationship among the QTc, the carotid IMT and the severity of CAD. Subjects and Methods: The QTc and the carotid IMT were measured in 165 consecutive patients TM system (GE Marquete Medical System, Milwaukee, USA) and the carotid IMT was measured by MATH software (METRIS Co., Argenteuil, France). The severity of CAD was divided into minimal disease (90, 54.5%), one-vessel disease (32, 19.4%), and multi-vessel disease (43, 26.1%), acording to the number of vesels that were narrowed by more than 50%. Results: The mean values of the QTc were 415.1?20.5 msec in the minimal disease group, 411.7?17.0 msec in the one- ?46.1 msec in the multi-vesel disease group. The QTc was correlated with age (r= 0.236, p= 0.002), HDL cholesterol (r= -0.160, p= .043), the right carotid IMT (r= 0.17, p=0.026), the left carotid IMT (r= 0.178, p=0.022) and the severity of CAD (r=0.243, p=0.002). On the multiple linear regresion analysis after adjustment for age and HDL cholesterol, the QTc was an independent factor for the severity of CAD. Conclusion: -rity of CAD and they may reflect the severity of the morphologic atherosclerotic surrogates.