Diazepam 10 and 20 mg, lorazepam 2.5 and 5.0 mg, flunitrazepam 1 and 2 mg, and a placebo, were compared in a randomized double-blind controlled trial as oral premedication for 210 patients undergoing minor gynaecological surgery. Flunitrazepam 1 mg and lorazepam 2.5 mg were superior to placebo (P less than 0.001 and P less than 0.05 respectively) in relieving patient anxiety when assessed by a trained observer 60 min after premedication. Flunitrazepam 1 mg also produced more drowsiness (P less than 0.01) than the placebo. Comparisons of other low-dose benzodiazepine groups with the placebo, and of the large dose with the small dose of each drug revealed no significant changes in anxiolysis or drowsiness. Dizziness and prolonged drowsiness were not apparent with low-dose flunitrazepam. The data suggests that flunitrazepam 1 mg offers advantages over placebo, diazepam 10 mg and lorazepam 2.5 mg for routine oral premedication in minor gynaecological surgery.