The PAP-(peroxidase-antiperoxidase)-immunohistochemical method was tested for rapid diagnosis on corneal specimens in clinically suspected herpetic disease. The method proved accurate, easy and useful in rapid diagnosis of corneal specimens from epithelial keratitis. Corneal buttons after keratoplasties for herpetic lesions were similarly tested for the presence of herpetic antigen. In a total of five corneal buttons, antigen was found in two corneas with necrotizing keratitis, whereas it was not noted in the three corneas opacified by disciform edema.