The effect of bright fluorescent light (115 fc) on oxygen-induced retinopathy in newborn kittens was compared with that of complete darkness and cyclic illumination of 12 hr of bright light (115 fc) and 12 hr of complete darkness. No significant difference was found in the extent of preretinal vasoproliferation and retinal ultrastructural findings among the three groups of kittens reared in different levels of illumination and a control group raised in a standard laboratory illumination level of 40 fc. These results confirmed that light is not a required factor for the development of oxygen-induced retinopathy in kittens.