We studied the effect of alprazolam (APZ) in 12 healthy volunteers on the psychological stress-induced activation of emotion and on the pituitary-adrenal, adrenomedullary and sympathoneuronal systems. After 3 days of placebo or APZ (1 mg/day orally) administration, we examined plasma levels of adre-nocorticotropic hormone, cortisol, L-3,4 dihydroxyphenylalanine, dopamine, norepinephrine (NE), epinephrine, metanephrine, normetanephrine, homovanillic acid, vanillylmandelic acid, 3-methoxy-4-hydroxy phenylglycol, urinary levels of cortisol and catecholamines, circulatory responses and state anxiety levels in subjects undergoing psychological stress based on viewing horror, violence, danger and war film clips. Film viewing produced modest rises of state anxiety levels, of plasma NE concentration and of diastolic blood pressure in both the placebo and drug groups. APZ significantly reduced anxiety levels at the beginning of the experimental session and caused a decrease of noradrenergic and dopaminergic neurotransmitter and cortisol concentrations. Our data suggest that APZ reduced anxiety related to the expectation of the event, while the circuitry between structures responsible for anxiety and peripheral sympathoneural function was still found to be partly sensitive to film viewing.