An instance of recurrent amaurosis fugax associated with atherosclerotic disease of the carotid siphon. One of these attacks was observed directly and another photographed. During these episodes the retinal vessels became quite attenuated, the optic disc and fundus blanched, and segmentation was apparent in the blood of the veins and arteries. Return of the circulation with recovery of vision was accompanied by retinal venous dilatation and hyperemia of the discs. This event is interpreted as an attack of retinal circulatory arrest and discuss its possible sense mechanisms.