Several corneal complications have been reported in patients with long standing diabetes, but their exact pathogenesis is not well understood. It has been observed that the rate of epithelial wound healing in diabetic rats is delayed compared to those in normal animals. Here we present the effect of the free radial scavenger, Trolox, a water soluble vitamin E analogue, on epithelial wound healing in diabetic rat cornea. Three groups of rats were included: 1) normal, 2) diabetic, 3) diabetic + Trolox. After 3 months, rats were sacrificed and corneas removed. Standard 3 mm diameter corneal epithelial defects were made and residual epithelial defects were measured after 18 hours at 37 degrees C in a sterile cell culture incubator. Wound healing data measured in mm2 was used for statistical analysis. There were significantly larger (p < 0.05) epithelial defects in diabetic corneas as compared to control. Treatment with Trolox antioxidant in diabetic rats produced a significantly smaller (p < 0.05) epithelial defect than that of untreated diabetic rats. These studies suggest the involvement of free radicals in the delay of corneal epithelial wound healing in diabetes.