The authors have tested the response of 24 female patients to experiments with dimethyltryptamine, using 1 mg./Kg body weight single dose. The majoority of the patients (20) were chronic schizophrenics. After presenting an analysis of 3 illustrative protocols the differences in response between normal test subjects and psychotics are discussed. Importance is attributed to the fact that in schizoplirenics the onset of vegetative symptoms was delayed, the vegetative manifestations were less intense and were even absent in 4 cases. The drug produced no new hallucinations. After-effects have not occurred. The reaction given by the non-schizophrenic psychotics was similar in course to that given by normal test subjects. The reduced sensitivity to dimethyltryptamine observed in schizophrenics suggests the possibility that a disturbance of cerebral metabolism is in the background of the psychic process of schizophrenia, as has been postulated by many authors in connection with LSD experiments. It is believed that the drug may prove to be a useful aid in the appraisal of prognosis in schizophrenia.