This essay discusses briefly the most important clinical applications of the multifocal electroretinogram (MERG). The MERG is used to provide a topographical and functional assessment of the retina. The essay discussed the use of the MERG in ocular hypertension and glaucoma, diabetic retinopathy and retinal detachment.In addition to the following macular disorders: Stargard’s macular dystrophy, occult macular dystrophy, and age-related macular degeneration. Then it investigated the MERG abnormalities occuring in retinitis pigmentosa, congenital stationary night blindness, branch retinal artery occlusion and the assessment of macular function before and after macular whole surgery. Finally, the MERG changes in acute idiopathic blind spot enlargment, multiple evanescent white dot syndrome, and myopia and vigabatrin toxicity are discussed.