In the present study, we have assayed the enzymatic activity of Cu,Zn-SOD, Mn-SOD, GSH-Px, GSH-Red, Cat, and G6PD in rat retina as a function of age. Conjugated diene levels and MDA formation were also determined. The conjugated diene levels in rat retina were found to increase significantly with age, accompanied by a marked decrease in GSH-Px and Cat activities. No age-related change in MDA levels and in GSH-Red and G6PD activity was found, whereas a significant increase in SOD activity was observed between 1 and 4 months. Decreased GSH-Px and Cat activity is related to increased lipid peroxidation with age.