Epithelial healing problems and basement membrane abnormalities have been observed in the corneas of patients with diabetes mellitus. In this study the rates of corneal epithelial wound healing following transcorneal freezing (with a 6-mm-diameter probe cooled in liquid nitrogen) were compared in diabetic (alloxan-induced) and nondiabetic rabbits. Also compared was the extent of injury to the epithelial basement membrane between the two groups. The overall rate of wound healing was faster in the diabetic animals; the wounds closed at 40 hours after freezing in diabetic animals and at 45 hours after in the nondiabetic controls. The lamina densa of the basement membrane was removed by the freezing procedure in two thirds of the diabetic animals but not in any of the controls. The results of this study indicate that epithelial healing problems in diabetes may be related to damage to the basement membrane, with resulting poor adhesion of regenerating epithelial cells.