A patient with Best's vitelliform macular dystrophy in his right eye had an intact vitelliform disk and drusen of the optic papilla. Although the foveola elevated by a few tenths of a millimeter, resolution was only slightly affected and the retinal receptors remained remarkably well-aligned, suggesting that mechanisms subserving receptor alignment still functioned. Hue discrimination and visual acuity were only slightly affected and the electroretinogram and visually evoked response showed essentially normal values. The vitelliform disk in the left eye ruptured by direct, blunt trauma. This same eye later developed subretinal macular neovascularization, as its visual acuity reduced, retinal sensitivity decreased, receptor orientation showed abnormalities, and hue discrimination became less efficient; the electroretinogram and visually evoked response remained normal.