The rate of reepithelialization of the rabbit cornea, receiving isotonic NaCl solution and acetylcysteine (Mucomyst) solution at 10 and 20% concentrations, following a superficial epithelial ulcer was studied by fluorescein staining, photography and light microscopy. Acetylcysteine solution does not seem to retard normal epithelial healing compared with control animals which received isotonic NaCl solution.