Alprazolam has been suggested as an adjuvant to neuroleptic drugs in the treatment of schizophrenic patients. In an attempt to investigate whether alprazolam has an effect on dopaminergic neurotransmission, plasma homovanillic acid concentrations were measured for 24 h following a challenge with 3 mg of alprazolam or placebo in eight healthy subjects. Alprazolam had no effect on plasma homovanillic acid which may suggest that this agent is devoid of activity at the dopaminergic system in normal subjects.