1. Psychotic manifestation: play a very important part in the mental disorders of old age, and occur in more than half of all the cases examined. 2. The commonest reaction is a persecuted one, but depression and hypochondria are also common. Mixed states are typical. The idea of being killed recurs again and again. 3. Seven illustrative cases are described, and an attempt is made to evaluate the symptoms from the psycho- analytic point of view. 4. General conclusions are drawn from these cases. Evidence is adduced of defensive efforts, with narcissism, flight from reality, repression, regression, projection and introjection. 5. The hypothesis is put forward that senile psychosis represents typically a defence against the fear of death, conceived of as a deprivation. 6. The suggestion is made that somewhat similar mechanisms may be found to be operative in producing some of the symptoms of senile dementia.