In a randomised, double-blind, parallel groups study, 40 patients referred for surgical removal of impacted third molars received either (a) temazepam 40 mg orally followed at 35 min by IV saline or (b) oral placebo followed by IV diazepam 10 mg (Diazemuls). Patients were divided into High-Anxious and Low-Anxious groups by median split of their anxiety scores on the Speilberger State Anxiety Scale at the time of oral medication. Compared with placebo, temazepam significantly attenuated anticipatory anxiety in the High-Anxious group while in the Low-Anxious group no difference was found between the treatments. Preoperative but not intraoperative heart-rate distinguished between the High-Anxious and Low-Anxious groups and neither oral temazepam nor IV diazepam abolished the heart-rate response to the traumatic stages of the surgical procedure. The results are interpreted as providing support in a "real life" human stress setting for Gray's neuropsychological model of anxiety.