A patient with hebephrenic schizophrenia who had kept silent for 26 years and a patient with simple schizophrenia who had remained silent for three years were reported. It was presumed that this mutism would be one of the symptoms of psychotic speech disturbance. Discussion was centered on the possibility that this mutism is one of the ways of expressing autism by communicating with society nonverbally and that this mutism can be interpreted as selective negativism.