Plasma norepinephrine (NE) and dopamine-beta-hydroxylase (DBH) activity may be altered by changes in posture, pulse rate, and BP. Twenty-three drug-free schizophrenic, ten schizoaffective, and 24 normal control subjects, and a separate group of eight schizophrenic patients treated with chlorpromazine hydrochloride and haloperidol comprised the sample. Drug-free schizophrenic patients showed higher plasma NE levels while standing and higher pulse rates when supine and standing than normal subjects. Following chlorpromazine therapy, but not following haloperidol treatment, plasma NE level increased with patients supine and standing, pulse rate increased with patients standing, and systolic BP decreased with patients standing. These findings suggest (1) a decreased peripheral alpha-adrenergic postsynaptic receptor sensitivity in schizophrenia and (2) a peripheral alpha-adrenergic blocking mechanism in chlorpromazine-induced hypotension.