A 21-year-old woman had typical clinical and biochemical findings of the cherry-red spot-myoclonus syndrome. She had 20/50 acuity in each eye, flutter-like ocular oscillations, rebound nystagmus, and transient vertical dissociation. Cherry-red maculas and optic atrophy were present. Although electroretinographic signals were normal, visual evoked potentials were almost absent. Levels of neuraminidase were significantly reduced in cultured ebroblasts from the patient and her parents, while lysosomal inclusions probably containing oligosaccharides were found in her conjunctival fibroblasts.