Endothelium plays a pivotal role in the development of atherosclerosis. Endothelial dysfunction participates in the course of acute coronary event. Using high-resolution ultrasound technique, endothelial dysfunction has been demonstrated in patients with atherosclerosis and risk factors for coronary disease, such as hypertension, diabetes mellitus, hypercholesterolemia and being smokers. In the present study, using this non-invasive method, the endothelial function of the brachial artery of patients with coronary heart disease (CHD) (n = 71) and control subjects (n = 34) was investigated. The results showed that endothelium-dependent and -independent vasodilatation were impaired in patients with CHD (2.61+/-2.91 vs. 8.10+/-7.81%, 17.20+/-7.93 vs. 23.19+/-8.89%, respectively) (P<0.001). Flow-mediated dilation (FMD) was significantly positively correlated with nitroglycerine-induced dilation (P<0.001). On univariate and multivariate analysis, the extent of FMD was significantly correlated with serum HDL-C levels (P<0.01). In conclusion, our study indicates both endothelial and underlying smooth muscle functions were impaired in patients with CHD. Decreased HDL-C levels may impair endothelial function.