The clinical presentation and electrophysiological findings are described of three consecutive cases with pericentral pigmentary retinal degeneration. The responses to bright flashes after dark adaptation showed negative waveform shape in all cases. Rod responses were strongly reduced compared with cone responses. Cone electroretinograms elicited by long-duration stimuli showed greater loss of the on-response than the off-response. The ratio of the on-response amplitude to off-response amplitude of these patients ( 0.52 +/- 0.12; mean +/- SD, n = 6) was significantly smaller than that of normal subject ( 0.83 +/- 0.21; mean +/- SD, n = 8) ( Mann - Whitney U-test, P < 0.01). The electrophysiological findings of these cases suggest a greater defect of inner retinal function, especially in transmission between photoreceptors and depolarizing bipolar cells.