Charcot was the first to notice the occurrence of amnesia in some of his patients suffering from alcohol-neuritis. Korsakow studied this peculiar kind of amnesia more elaborately. He regarded this condition as a disease sui generis, which could arise also from other causes besides abuse of alcohol, and used the name “polyneuritic psychosis.” It was later recognised that the same mental picture could exist without accompanying neuritis. Jolly proposed the name “amnestic” or “Korsakow's” syndrome, regarding it as a modus of reaction of the nervous system to various harmful agents, viz., head-trauma, senium, infections, poisons—alcohol being the most frequent cause of this reaction. Most later writers agree with this view. I shall deal in this paper with the cases of thirty patients, who, at some time during their illness, presented this syndrome; I have not included any cases in which alcohol could not be regarded as the principal factor.