Purpose: Elevated serum level of low-density cholesterol (LDL-C) is known to be associated with an increased risk of coronary artery disease (CAD) and are currently recommended as the primary target for lipid-lowering therapy for prevention and treatment of cardiovascular disease. However, a number of patients with CAD have low or normal LDL-C. In our study, we evaluated the significance of high-density lipoprotein cholesterol (HDL-C) in patients with low LDL-C using the presence, extent of CAD on multidetector computed tomography (MDCT). Methods: 119 patients with LDL-C levels below 70mg/dl were studied. The patients were classified into no CAD, non-obstructive CAD (luminal stenosis < 70% and obstructive CAD ( luminal stenosis ��� 70%). And the number of segments with coronary plaque on MDCT was evaluated. Results: Significantly lower values of HDL-C were observed in patients with CAD compared with no CAD ( 44.05짹15.32 vs 54.10짹17.44, p=0.001). The level of HDL-C in patients with obstructive CAD were significantly lower than non-obstructive CAD (IMT-0.82짹0.19mm vs. 0.76짹0.16mm, PS-3.03짹5.42 vs. 2.15짹3.25, respectively, p<0.001). Other lipid levels including total cholesterol, triglyceride, apolipoprorotein A1, apolipoprotein B, and lipoprotein a were not significantly different according to the presence and obstructive CAD. Extent of coronary plaques presenting as the number of segments with plaques was negatively correlated with HDL-C PS (r=-0.298, p<0.001). On multivariate regression analysis after adjustment significant traditional cardiovascular risk factors, HDL-C level was independent predictor for the presence of CAD and obstructive CAD (OR 0.951, p=0.001 and OR 0.946, p=0.003) regardless of current lipid-lowering therapy. Conclusions: Our data suggest that HDL-C level might be useful predictor for the presence, severity and extent of CAD in patients with low LDL-C level.