An unusual form of retinal degeneration is reported in 15-year-old girl and 11-year-old girl with different pedigrees, which resembles the cases reported by Gouras and associates (1983). The subjective symptoms in these patients included decreased visual acuity, photophobia, anomalous color vision and night blindness. Electroretinograms (ERGs) in these two patients were identical in substance and revealed drastic alterations in both photopic and scotopic functions. The stimulus versus intensity response curve in a single-flash ERG showed an unusual form. This peculiar supernormal response was elicited by bright stimuli although the stimulus threshold was extremely elevated.