A form of combination anaesthesia using ketamine, diazepam, alcuronium and nitrous oxide was used in 41 patients over 65 years requiring abdominal surgery. The patients were premedicated with droperidol 2.5-7.5 mg im. At induction the patients received diazepam 5 mg. ketamine 2 mg/kg and alcuronium 0.2 mg/kg. Anaesthesia was maintained with a continuous, steady injection of ketamine 2.5 mg/kg/h and nitrous oxide-oxygen with controlled ventilation. Four minutes before incision the patients received 1 ml of coded solution and at the end of anaesthesia the same solution, which contained either 5 mg/ml diazepam or its solvent only. There were no statistically significant differences between the two groups, i.e. patients receiving either 15 or 5 mg of diazepam. The incidence of bad dreams was 5 per cent, i.e. one patient in each group. Only one patient vomited and one had pronounced nausea in group D5. According to the anaesthesiologist's, the anaesthesia nurse's and the patient's subjective evaluations this type of combination anaesthesia was found to be highly acceptable. Despite there being no statistically significant differences between the patients who received 5 + 5 + 5 mg of diazepam compared to those receiving 5 + 0 + 0 mg, the figures in results per se incline in favour of the use of 5 + 5 + 5 of diazepam.