Experimental trials with DMT have been carried out in 24 female patients at our department, a single dose of I mg/kg being administered in every case. In 3 cases the experiment was repeated with single doses of 1.5 mg/kg. The age of the patients varied from 24 to 53 years. The majority of the test subjects had been suffering from chronic schizophrenia for 3 to 20 years (20 cases). Also included in the trials were 2 cases of oligophrenfa, 1 case of psychopathy, and I case of conversion hysteria. The differences in the manifestations of the DMT psychosis between normal and psychotic experimental subjects may be outlined as follows: (1) It was remarkable that, as compared with the normal test subjects and the 4 non-schizophrenics, the schizophrenic patients developed the vegetative symptoms about 3 to 4 Ininutes later. There was no such difference between the normal test subjects and the patients suffering from mental diseases other than schizophrenia. Even this relatively small difference in time seems to be a highly important feature, in view of the rapid onset and course of the DMT effect. (2) In schizophrenics the vegetative symptoms were less marked and 4 patients showed no such symptoms at all. In the latter cases, behaviour suggested no pathological experience, either. (3) Except for a sensitive borderline case, schizophrenics did not respond to DMT with hallucinations, whereas all the 4 non-schizophrenics did. (4) Changes in the affective state and behaviour did not reveal any after-effect in the cases of schizophrenia, neither were pertaining subjective experiences related by the patients.