Oxidized low density lipoprotein (oxLDL) plays a pivotal role in the development of atherosclerosis. The aim of the study was to investigate the relationship between oxLDL and other oxidative stress biomarkers with stable coronary heart disease (CHD). We compared the degree of oxidative stress in patients with CHD and sex-matched healthy control subjects in a case-control study. The study included 64 male subjects: 32 patients with stable CHD and 32 normal control subjects. Levels of circulating oxLDL were measured by a monoclonal antibody 4E6-based competition ELISA. Comparison of oxidative stress marker levels between cases and controls, adjusted for age, revealed significantly higher plasma oxLDL levels (63.32+/-25.49 vs. 37.73+/-20.58 U/l, P=0.001), lower serum levels of autoantibodies against oxLDL (341.53+/-350.46 vs. 796.45+/-1034.2 mU/ml, P=0.021), higher activities of the antioxidant enzymes superoxide dismutase in erythrocytes (951+/-70.2 vs. 771.6+/-191.2 U/g, P=0.032) and glutathione peroxidase in whole blood (GSH-Px: 10714.4+/-3705.4 vs. 5512.2+/-1498.1 U/l, P<0.001). The risk of having CHD was 20.6-fold greater (95% CI, 1.86-228.44, P=0.014) in the highest tertile of the oxLDL distribution than in the lowest, determined by logistic regression analysis on the combined study population after adjustment for age and other potential confounding factors. When the risk associated with GSH-Px levels was calculated, the odds ratio was 305.3 (95% CI, 5.07-18369.95, P=0.006) in the highest tertile compared with the lowest. Our results showed that an oxidative stress occurs in patients with CHD despite being clinically stable and under medical treatment. The combination of oxLDL levels and GSH-Px activity may be useful for the identification of patients with stable CHD.