Sodium cyanide intoxication of rats produced demyelinative and necrotic lesions in the corpora callosa in 70% and the optic nerves in 20%. The optic neuropathy was bilateral, focal, and retrobulbar. All animals with optic neuropathies had marked callosal lesions. Chiasmal involvement was rare. Certain features of experimental cyanide intoxication negate the possibility that cyanide is responsible for human optic nerve diseases.