Dimethyltryptamin was synthesized and its effect on psychosis investigated. An intramuscular injection of 0.7-1 mg/kg Dimethyltryptamin was given and after 3-5 minutes a psychotic condition was induced which in many respects resembled those phenomena induced by mescalin and LSD 25. This Dimethyltryptamin psychosis lasted less than an hour. Besides a description of the symptoms we have investigated three problems: 1. The reason for the swift start and rapid departure of the psychosis. 2. What is the significance of the one-sided nature of the symptoms, that is, the greater degree of disturbance in the right non-dominant hemisphere when the psychopathological phenomena begin to show. 3. Having regard to the close chemical affinity between Dimethyltryptamin and Serotonin, what conclusions could be drawn as to the import of serotonin metabolism in the C.N.S. Further experiments should clarify the similarities and differences between psychoses induced by Bufotenin and those by Dimethyltryptamin.