In a series of 22 eyes of 19 squirrel monkeys, the central retinal artery (CRA) was ligated within the orbit. Serial fundus photography and fluorescein angiography demonstrated that this experimental model closely resembled the human disease. Histologically, there was massive swelling of the inner retinal layers followed by necrosis. Fine-structurally, CRA occlusion produced mitochondrial swelling in neurons of the inner retinal layers within 15 minutes. This was followed by swelling of the endoplasmic reticulum and cell cytoplasm. By 3½ hours there was clumping of nuclear chromatin and rupture of cytoplasmic membranes. After 16 hours autolysis of all cells vitread to the outer nuclear layer was far advanced. Müller cell cytoplasm was relatively resistant to ischemia in the early stages but not in the later stages. The photoreceptor cells were spared.