The possibility of epithelial injury of BALB/C mice cornea exposed to a cathode ray tube (CRT) of a commercially available television was investigated. Epithelial injury of the cornea was confirmed by fluorescein-positive staining after 24 hours of CRT exposure approximately 3-9 cm from the surface of the CRT. The corneal epithelial injury was shown to be mainly limited to the most superficial layer by transmission electron microscope finding showing slight deterioration of the basal cell layer. The corneal epithelial defect was further measured by a scanning electron microscope in relation to the time of exposure to the CRT. The impaired area increased in dose-dependent manner to the some extent. The epithelial defect increased at 5 hours of CRT exposure and reached a maximum, that is 46.6% of the entire area of the cornea, by 12 hours of exposure, thereafter maintaining an equilibrium. The mechanism of corneal epithelial injury by CRT was discussed.