The safety and efficacy of alprazolam and hydroxyzine administered orally as surgical premedicants were compared in a double-blind controlled study. Sixty-five patients were given either alprazolam 1 mg or hydroxyzine 75 mg, one to two hours before surgery. Anxiety was assessed by both the patient and the anaesthetist, the patient using a visual analogue scale, the anaesthetist employing both analogue and ordinal ratings. Sedation was assessed by the anaesthetist only, using the same two methods. Amnesia was appraised with a simple memory test. Safety was assessed by recording adverse effects and measuring haemodynamic variables. Premedication with alprazolam produced a modest reduction in anxiety (28%) (P < 0.01) while hydroxyzine had no detectable effect. The comparison of the sedation level and of the memory test revealed no difference between the two premedicants. Minor side effects were only observed in the hydroxyzine group. Changes in blood pressure were more pronounced in the hydroxyzine group. This study shows that alprazolam and hydroxyzine are safe and efficient oral premedicants. However, alprazolam is preferable to hydroxyzine in terms of anxiolytic and adverse effects.