Among one hundred fifty schizophrenic patients who were treated with metrazol or insulin shock, those who were previously judged as having a favorable prognosis usually responded well to shock treatment, while patients with a poor or doubtful prognosis gained little or nothing. The various prognostic criteria are analyzed. Short duration of illness and absence of any process symptoms are the most important favorable factors. Other favorable criteria are the presence of manic-depressive features, acute beginning, clear-cut exogenous precipitating factors, a variation in the structure from that of previous psychotic episodes, prevalence of catatonic traits, pyknic body formation and extraverted character. Prepsychotic adjustment, age, sex, and family history are of lesser value as prognostic criteria.