We examined five patients who had carbohydrate-deficient glycoprotein syndrome with full-field electroretinograms. Only two of the patients showed fundus changes typical for retinitis pigmentosa, whereas abnormal electroretinograms were seen in all patients. There was no recordable rod response; however, a delay in the cone b-wave implicit time was noted. All patients had nyctalopia. These observations suggest that patients with the carbohydrate-deficient glycoprotein syndrome have a progressive tapetoretinal degenerative disorder of the retinitis pigmentosa type with defined alterations in the electroretinogram.