To compare the multifocal electroretinogram (ERG) system to conventional ganzfeld and focal ERGs obtained from patients with known retinal diseases to assess its clinical applicability.A multi-input system analysis was used to explore the field topography of ERG responses to local luminance modulation in patients with retinitis pigmentosa, pericentral pigmentary retinal dystrophy, branch retinal arterial occlusion, or idiopathic macular hole.The dysfunctional areas measured by multifocal ERG were compatible with those assumed by combined findings of ganzfeld and focal ERGs. However, the wave shapes of multifocal ERG in the retina with arterial occlusion differed from those of conventional focal ERG, suggesting that the negative and positive deflections shown in the first-order kernel of multifocal ERG may not correspond to conventional a- and b-waves of ERG.The multifocal ERG system is available for electroretinographic field mapping at the clinical level.