The rate of corneal epithelial wound healing has been shown to be faster in diabetic than in normal rabbits when the epithelial cells are removed by scraping or freezing; both methods of epithelial removal, however, damage the basement membrane in corneas of diabetic but not normal rabbits. In this study, we compared the rate of wound healing and the increase in corneal thickness in normal and diabetic rabbits in which the epithelial cells were removed with heptanol, a method that does not damage the basement membrane in either group. In addition, the effect of tretinoin on the rate of wound healing was compared in both groups. There was no statistical difference between the rate of epithelial healing in the untreated control and in untreated diabetic eyes. Treatment with tretinoin resulted in a significant increase in the rate of healing in control but not in diabetic eyes. Corneal thickness increased in all groups after epithelial removal, but the increase was significantly less in the corneas of diabetic rabbits at 24 hours. These results indicate that tretinoin may be more effective in promoting epithelial healing in eyes of normal patients than in diabetic patients.