VEP is an objective method for the evaluation of macular function and optic nerve disease, but its large inter and intraindividual variation prevented clinical and experimental application. We recorded a relatively stable VEP A wave in pigmented rabbits with cortical electrode and following results were obtained. The amplitude of VEP A wave was 97.8 +/- 29.8 micro V and latent time was 52.2 +/- 6.9 msec. Inter- and intraindividual variation of VEP latent time was much smaller than that of VEP amplitude. So latent time of VEP A wave may be a good indicator in evaluation of pharmacologic and toxicologic experiment of systemically administered drug.