1. The investigation showed that many etiological factors may underlie the production of amnesia and loss of identity.2. In the 104 cases studied, the great classifications were organic brain disease, functional mental disease, the psychoneuroses, exogenous and endogenous toxæmias, epilepsy, and malingering.3. Males constituted the great bulk of the cases, with the exception of the psychoneurosis-hysteria and the malingering group, where females predominated.4. Among the negro race, females constituted the great majority of the patients, very few negro males developing amnesia.5. The most melodramatic and interesting cases were those that were of an hysterical or epileptic genesis.6. In children, the condition occurred only when constitutional mental inferiority was present.7. The ratio of amnesia cases to total cases admitted in an acute psychopathic hospital service was 1:120.