The aim of the study was to investigate the levels of lipid peroxidation, and both plasma and erythrocyte antioxidant states in patients with rheumatoid arthritis. The population consisted of 60 subjects divided into two groups, 30 subjects had evidence of rheumatoid arthritis and age and sex matched healthy subjects were studied as controls. The level of plasma and erythrocyte thiobarbituric acid reactive substances (TBARS) was markedly increased in both the rheumatoid arthritis patients when compared to control subjects. The activities of plasma and erythrocyte antioxidants were significantly decreased in rheumatoid arthritis.