Cardiovascular measurements were used as indicators of autonomic arousal during an orthostatic challenge test without medication and after a test dose of 150 mg perazine in 20 acute schizophrenic patients. Unmedicated schizophrenics showed elevated heart rates and elevated systolic and diastolic blood pressure in comparison to healthy volunteers. After a test dose of 150 mg perazine, responders (using BPRS outcome criteria after 23 days) showed a pronounced orthostatic heart rate reaction in comparison to nonresponders. Results are discussed in relation to arousal theories and central dopaminergic activity in schizophrenia.