In this study membrane lipid peroxidation in erythrocytes cf fifteen diabetic patients and its correlation with plasma glucose was studied. Diabetic patients were eight males and seven females. Their ages ranged 20-45 , with a mean value of 30 3.5 years. All patients in this study were insulin dependent diabetics, except 2 who had non insulin dependent diabetes. Another fifteen healthy subjects volunteered as controls. Their ages ranged 23-46 with a mean value of 29+ 4.1 years. Lipid peroxidation was estimated by quantitafing malondiaidehyde (MDA), an end prod uct of lipid peroxidation. Erythrocytes of diabetics showed a significantly higher (P«O.OS) malondialdehyde level compared with non diabetic erythrocytes. The degree of membrane lipid peroxidation in erythrocytes was significantly correlated with the level of glycosylated hemoglobin. ( r 0.81, PK 0.05), This suggests that peroxidation of membrane lipids and accumulation of MDA occurs in erythrocytes of diabetic patients.