Albino rats were maintained in 60% atmospheric oxygen from birth through 14 days of age. Age-matched controls were simultaneously raised in room air. Some rats were perfused with India ink before sacrifice and retinal dissection in order to study the effect of oxygen-rearing on the retinal vasculature. By this method it was found that oxygen-reared animals sustained a 36% loss of retinal blood vessels. Other animals' retinas were removed immediately after sacrifice and examined for evidence of lipid peroxidation by one of three means: 1) a determination of the presence of products of lipid peroxidation, 2) a measure of the loss of polyunsaturated fatty acids, and 3) a determination of retinal vitamin E level. Each of these determinations indicated that peroxidation reactions had occurred in the retinas of oxygen-reared rats. Retinal vitamin E was supplemented in the young rats through the diet of the mothers. This treatment resulted in a two-fold increase of retinal vitamin E over levels in pups of mothers fed rat chow. Oxygen-reared vitamin E-supplemented rats sustained significantly less obliteration of blood vessels than non-supplemented oxygen-reared animals.