Since the distribution of the retinal nerve fiber layer (RNFL) is not regular, this study was performed to evaluate the normal regional variation in its ophthalmoscopic appearance. Wide-angle red-free photographs of the RNFL and color stereo optic disc slides of 195 normal eyes of 119 subjects were morphometrically examined. The RNFL was most visible in the temporal inferior sector, with the neuroretinal rim being correspondingly broadest (P < 0.001) and the diameter of the corresponding retinal artery the widest; these parameters were found to diminish appreciably in the temporal superior sector, the nasal superior sector, and the nasal inferior sector in this order. The visibility of the RNFL in a particular region therefore correlates positively with the rim width and retinal artery caliber in that region, the RNFL being most detectable in the temporal inferior part of the fundus. This may be important in the evaluation of eyes with optic nerve damage.