We report the ophthalmological findings of two sisters with severe glutathione synthetase deficiency, an autosomal recessive inborn error of metabolism resulting in very low intracellular levels of the free-radical scavenger glutathione. The patients were investigated because of declining visual acuity. The most prominent finding was progressive retinal dystrophy with hyperpigmentations and maculopathy. Generally disturbed functioning of both the outer and inner layers of the retina resulted in attenuated or nearly abolished electroretinograms. These findings agree with a rod/cone type of retinal dystrophy, and we suggest that this is due to glutathione deficiency. Treatment with antioxidants such as vitamins E and C seems to prevent the progression of CNS damage. We speculate that it might also prevent retinal dystrophy in patients with glutathione synthetase deficiency. We suggest that patients with retinal dystrophy and additional neurological signs should be investigated for a defect in glutathione metabolism. Also, we recommend that patients with low levels of glutathione should be examined for retinal dystrophy. Our results suggest that a decreased capacity for scavenging reactive oxygen species and/or increased oxidative stress may cause retinal dystrophy. If this is the case, the redox state in the retina should be a potentially useful therapeutic target to prevent reduced visual function and blindness.