Premedication with lorazepam (4 mg), diazepam (10 mg), and a placebo was compared in a randomized, double-blind study of 95 adult surgical patients. Comparisons were made of recall of a memory card and events of the operative day, relief of anxiety, degree of somnolence, effects on blood pressure and heart rate, and incidence of side effects. Lorazepam produced a significant lack of recall (antegrade amnesia) compared to the other agents. Lorazepam produced a greater antianxiety effect than placebo and a greater degree of somnolence than diazepam or placebo. Since no adverse effects on blood pressure or heart rate occurred, lorazepam appears to show promise as a premedicant.