The labeling index and the mitotic rate were measured at 4-hour intervals during the first 24 hours after a central abrasion had been made in the corneal epithelium of six groups of four rats each. The proliferative response was noted in the conjunctival, the limbal, and the corneal epithelium. After 24 hours, the density of epithelial cells was equal throughout the corneal epithelium, but there was only half the normal number of cells. Physiological mechanisms seem strongly to regulate the total number of cells per square unit throughout the healing corneal epithelium, but the nature of these mechanisms is unknown.