Background and Objectives: Arterial stiffness is a valuable predictor of coronary artery disease (CAD) and pulse wave velocity (PWV) is one of reliable markers for arterial stiffness. The aim of this study is to evaluate that PWV predicts the severity of CAD such as the number of diseased vessel and presence of calcification. Methods and Results: Regional PWV were measured by noninvasive automotive device in normal control group (n=197) and in patients with angiographically more than 50% coronary stenosis (n=198). Biochemical markers including hs-CRP, adiponectin, and lipid profiles were analyzed. The levels of central arterial (carotid-femoral artery:cf) PWV of the CAD group were significantly higher than the control group (8.52짹1.32m/s vs. 7.81짹0.77m/s, P<0.01) although the mean blood pressures of the CAD group were controlled below those of the control group (88.93짹11.39mmHg vs. 94.95짹12.97mmHg, P<0.01). The levels of peripheral arterial (femoral-dorsalis pedis artery and carotid-radial artery) PWV were not significantly different between CAD and control group. In the CAD group, the levels of cfPWV was higher in patients with diabetes compared with the control group (8.98짹1.52m/s vs. 8.28짹1.14m/s, P<0.01). The levels of cfPWV was higher in patients with three-vessel disease compared with one or two-vessel disease (9.06짹1.44m/s vs. 8.11짹0.99m/s, P<0.01) in non-diabetec group, but there were no differences among diseased vessel numbers in diabetic CAD group. The levels of cfPWV of the patients with calcified coronary vessels was significantly elevated in both diabetic (9.94짹1.28m/s vs. 8.63짹1.46m/s, P=0.01) and non-diabetic CAD groups (8.87짹1.33m/s vs. 8.18짹1.08m/s, P=0.014.). The levels of plasma adiponectin which is known to have anti-atherosclerotic properties are decreased in CAD group (3.73짹2.41ug/ml vs. 6.69짹3.37ug/ml, P<0.01). Conclusions: These data showed that diabetes can strongly affect arterial stiffening and central arterial PWV may be a predictive marker of the severity as well as the presence of CAD.