Clobazam 20 mg, diazepam 10 mg, lorazepam 2 mg and oxazepam 30 mg were compared in a randomized, double-blind, placebo-controlled trial as oral premedication for 150 patients undergoing minor gynaecological surgery. All drugs and placebo significantly decreased anxiety when assessed by the patient on a 10-cm linear analogue rating scale 60 min after premedication. Diazepam 10 mg induced significantly more drowsiness when assessed by a trained observer 60 min after premedication than clobazam 20 mg, oxazepam 30 mg and placebo (P less than 0.01). Lorazepam 2 mg caused significantly more drowsiness 2 h (P less than 0.001) and 4 h (P less than 0.01) after operation, and significantly impaired psychomotor function after operation compared with the other four agents. The data suggest that clobazam 20 mg, diazepam 10 mg, oxazepam 30 mg or placebo offer advantages over lorazepam 2 mg for oral premedication in minor gynaecological surgery where early discharge after operation is preferred.