Occlusion of the central retinal artery (CRA) in squirrel monkeys led to a rapid depression of both the b-wave of the electroretinogram and the optic tract discharges evoked by photic and electrical stimulation. The optic tract discharges were completely abolished within two minutes but a small b-wave remained even after 3.5 hours of occlusion. For occlusion periods of less than two hours, return of blood flow to the retina resulted in complete recovery of the electrical signals from the retina and the optic tract. After 3.5 hours of occlusion, there was partial recovery of the b-wave but no return of the optic tract responses. These changes were correlated with earlier studies of the fine structure of the retinal elements which showed rupture of the cytoplasmic membrane of the axons in the nerve fiber layer after 3.5 hours of occlusion.