Pathogenesis of occlusion of the central retinal vessels, based on experimental and clinical findings, is discussed. It suggests that the so-called "central retinal vein occlusion" represents not only occlusion of the central retinal vein but also retinal arterial ischemia. Based on this pathogenesis the following terminology is recommended for central retinal vascular occlusion: (a) Ischemic retinopathy is due to occlusion of the central retinal artery. (b) Venous stasis retinopathy is due to occlusion of the central retinal vein alone. (c) Hemorrhagic retinopathy is due to occlusion of the central retinal vein associated with retinal ischemia. Clinical findings of (b) and (c) are compared which indicate that the two conditions are distinct entities and unfortunately so far have been dumped under a common heading of so-called "central retinal vein occlusions". Such a distinction is extremely important before any attempts are made to evaluate their natural history or effects of any therapy on them.