Diabetes mellitus is one of the most common metabolic disorders that causes micro- and macro-vascular complications. The lens and skin, as well as most other organs, suffer as a result of metabolic disturbances caused by diabetes. Early diagnosis of diabetic skin and lens complications can be prevented or treated. Vitamin C ,which is an important antioxidant in human, is capable of scavenging oxygen-derived free radicals. The aim of this study was to investigate the effect of vitamin C on the lens and skin of streptozotocin-induced diabetic rats. Vitamin C, 80 mg/kg/day, i.p., was given to both diabetic and control rats daily, until the end of the experiment. 8 days after the diabetes induction, the total protein, nonenzymatic glycation of proteins (NEG), lipid peroxidation (LPO), and glutathione (GSH) levels in the lens and skin homogenates were determined by the methods of Lowry, thiobarbituric acid, Ledwozwy, and Ellman, respectively. Laemmli SDS polyacrylamide gel electrophoresis was also carried out on the lens or skin homogenates. Uncontrolled induced diabetes caused significant increases in blood glucose (p<0.01), NEG of skin and lens proteins, significant increase in skin LPO(respectively, p<0.01, p<0.05, p<0.05) and significant decrease in lens GSH (p<0.01). SDS-polyacrylamide gel electrophoresis revealed no significant differences in any protein bands between any of the groups. As vitamin C, in dose we used, did not reduce blood glucose level, it could not reverse the diabetic alterations of the skin and lens parameters in rats.