1. A series of observations carried out on clinical material seems to justify the delimitation of a clinical picture for which the name of senile encephalomyelosis is suggested.2. The symptoms of senile encephalomyelosis are acute or sub- acute mental disturbances of the organic reaction type, usually associated with posterolateral sclerosis (rarely transverse myelitis or spastic spinal paralysis), sometimes associated with polyneuritis and very often associated with hypochromic or hyperchromic anemia, with or without gastric anacidity (hypoacidity).3. Senile encephalomyelosis appears to be much more frequent in women than in men.4. The relationship of senile encephalomyelosis to senile anorexia, primary cachexia, senile hypochromic achylic anemia and pernicious anemia can be established.5. Hypervitaminization, particularly treatment with vitamin B1, liver extract and nicotinic acid, seems to give very good results.6. Every case of so-called senile delirium or of the apparent confusional and hallucinatory type of senile dementia should be examined from this point of view and tentative hypervitaminization should be instituted.7. The pathogenesis of senile encephalomyelosis is unknown. A possible hypothesis, however, is that hormonal and more especially, pituitary disturbances might be responsible.