In the present study, erythrocyte membrane lipid peroxidation, erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and serum vitamin C levels of subjects with and without coronary artery disease (CAD) documented by coronary angiography have been determined. Patients consisted of 42 subjects (31 male, 11 female) aged between 41 and 77 years and controls consisted of 35 subjects (21 male, 14 female) aged between 40 and 69 years. Erythrocyte lipid peroxidation of the patients was significantly higher (P < 0.005) whereas erythrocyte SOD, GSH-Px activities and serum vitamin C levels were lower than those of controls. Our results show significant alteration in erythrocyte membranes and antioxidant status of patients with CAD. However, whether such alterations are a primary cause or consequence of CAD and whether these alterations can be used in the diagnosis and management of the disease needs further investigation.