The incidence rate and mortality of coronary heart disease (CHD) is obviously higher in men than in women, which may be related to the influence of plasma lipoprotein metabolism by endogenous sex hormones. We determined plasma testosterone (TTT), estradiol, total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), HDL2-C, HDL3-C, apolipoprotein (Apo) AI, Apo B100 and lipoprotein (a) [Lp(a)] in 201 subjects, among them 102 patients with CHD and 99 healthy subjects. It was found that, mean plasma TTT levels in patients with CAD (252+/-125 ng/ml) was significantly lower than in the healthy subjects (412+/-309 ng/ml). There was a negative association between plasma TTT level and plasma TG level (r=-0.239; P<0.001) and Lp(a) (r=-0.163, P<0.05), and a positive association between plasma TTT level and HDL-C (r=0.301, P<0.001) and HDL3-C (r=0.328, P<0.001). The results in the present study suggest that low plasma TTT level may be a risk factor for CHD, which may relate to the influence of plasma lipoprotein metabolism by endogenous testosterone.