Free oxygen radicals and subsequent lipid peroxidation are considered to be responsible for coronary artery disease. We conducted this study to determine the blood paramenters concerning the oxidative process in acute myocardial infarction. Plasma total antioxidant status (TAS), total cholesterol (TC), triglyceride (TG), high-density lipoproteins (HDL-C), low-density lipoproteins (LDL-C) and thiobarbituric acid reactive substance ((TBARS) levels were examined as well as erythrocyte TBARS and glutathione (GSH) in 20 patients with acute myocardial infarction (AMI) admitted to the Emergency Department in Instabul University, Istanbul Faculty of Medicine, and in healthy matched control subjects. As compared to healthy controls, plasma TBARS, T-C, TG and LDL-C levels were significantly elevated in patients with AMI (P < 0.01). There were significant associations between the HDL-C levels and TAS of patients and controls, positive correlations between erythrocyte GSH and TBARS, TC and LDL-C, TC and TG levels and a negative correlation between TAS and plasma TBARS. We conclude that oxidative stress may play an important role in acute myocardial infarction. (C) 1998 Chapman & Hall Ltd.