The eight topical antibiotic solutions that we use most frequently were tested for their effect on corneal epithelial wound healing in the rabbit. Five percent cefazolin sodium and a mixture of neomycin sulfate, polymyxin B sulfate, and gramicidin (Neosporin) had the least effect on epithelial healing rates and quality of healing, 10% sulfacetamide sodium and an artificial tear had intermediate effects, and gentamicin sulfate, tobramycin, and chloramphenicol were the most toxic. No substantial differences were found between gentamicin and the newer aminoglycoside, tobramycin, and the "fortified" preparations of these two drugs did not seem to be more toxic than the 0.3% solutions. Therefore, topical antibiotic solutions vary in their effects on the corneal epithelium, and not all antibiotics should be considered innocuous when used in the treatment of epithelial defects.