SummaryAmong cases with hallucinatory and delusional states, two cases with rapid onset, hypotension and slight disturbance of consciousness were studied. Under hallucinatory and delusional states, EEG showed low amplitude rapid waves. Administration of haloperidol with arousal action caused disappearance of hallucination and delusion as well as rapid waves, indicated the role of decreased activity of lower brain area in the development of hallucinatory and delusional states.In addition to the disturbance of emotional and volitional aspect, hallucination and delusion in schizophrenia might also be concerned with disharmony of activities of lower brain and cerebral cortex.