Thirty-five adult cardiac surgical patients received 20 mg dipotassium clorazepate orally the evening before surgery and 2 mg flunitrazepam 60 min before induction of anaesthesia. If anaesthesia was to be induced after 08.30 hours patients received an additional 20 mg dipotassium clorazepate at 06.15 hours. The following measurements were made: peripheral arterial oxygen saturation (Spo2) breathing room air; anxiety by visual analogue scale; degree of sedation; and haemodynamic variables. Mean (Spo2) was 95.9% (SD 1.8%) on the day before surgery and 95.4% (SD 1.5%) on arrival at the operating room. When the operation started after 08.30 hours, mean (Spo2) at 09.00 hours was 96.0% (SD 1.4%). There were no detected episodes of hypoxaemia after premedication. Mean anxiety score decreased significantly from 3.9 (SD 2.6) on the day before surgery to 3.3 (SD 2.1) on arrival at the operating room (patients' score; P < 0.002) and from 4.6 (SD 2.4) to 3.3 (SD 2.0) (anaesthesiologists' score; P < 0.001). Nearly all patients were considered well sedated, which was reflected by normal haemodynamic variables on arrival at the operating room. The combination of clorazepate and flunitrazepam is effective oral premedication for adult cardiac surgery, causing no obvious desaturation even when supplemental oxygen is not given.