Recent changes in the medical system have resulted in a significant increase of ambulatory surgical procedures. Therefore, a safe and short postoperative recovery period and, especially, the full recovery of complex psychological function after general anaesthesia have become increasingly important. In the present study we investigated the recovery of psychomotor and cognitive function after general anaesthesia with propofol/alfentanil and thiopentone/isoflurane/alfentanil. PATIENTS AND METHODS. Institutional approval and informed consent was obtained in 40 female ASA I or II patients undergoing diagnostic laparoscopy. As oral premedication the patients received chloracepat (10-20 mg) 45 min before the start of anaesthesia. Anaesthesia was induced in group I with propofol (2.5 mg/kg) and maintained with propofol (6-12 mg/kg/h)/alfentanil (0.05 mg/kg) and 50% N2O in O2. The patients of group II received thiopentone (5 mg/kg) for induction and isoflurane (0.5-1.5 vol%)/alfentanil (0.05 mg/kg) and 50% N2O in O2 for maintenance of general anaesthesia. In particular we measured the following parameters: (1) The recovery time, defined as the interval between the termination of the anesthetic and the patient's correct recall of her birth date. (2) The choice reaction times to optical stimuli (red or green light), which was used as a parameter for attention and psychomotor function. (3) The score in the "Zahlen-Verbindungs-Test" in which the patients had to connect numbers from 1 to 90 in correct order. This is also a parameter to quantify attention and psychomotor function. (4) The digit span which is a value derived from the number of correctly reproduced digits from a list presented to the patients. It is a measure of numerical memory. (5) The Munich Verbal Learning Test, which is the German version of the California Verbal Learning Test. It represents the number of correctly reproduced words from a previously presented list and is a measure of the verbal memory. (6) The Wisconsin Card Sorting Test, which serves to test the ability to plan and act and to form terms and concepts. (7) The State-Trait Anxiety Inventory, to quantify state anxiety. (8) Pain score, using a visual analogue scale. The tests were performed at four measurement points: the day before the operation and 30, 60, and 240 min after recovery. The "Zahlen-Verbindungs-Test", the digit span and the Munich Verbal Learning Test were presented in four parallel forms to minimize learning effects. For statistical analysis of the data the Wilcoxon test was employed within groups and the Mann-Whitney test between groups. RESULTS. The groups were comparable in age, weight, height and level of education. No significant difference was found between them in operation or anaesthesia time or in the total dosage of alfentanil. Recovery time in the propofol group was, at 10 min, significantly shorter than in the isoflurane group, with 16 min. Choice reaction times were significantly increased 30 min after recovery from anaesthesia in both groups. In the propofol group they returned to normal after 60 min, whereas in the isoflurane group significant increases could be observed even 240 min after recovery from the anaesthetic. Choice reaction times were significantly longer in the isoflurane group than in the propofol group 60 min and 240 min after anaesthesia. In the "Zahlen-Verbindungs-Test" the patients showed significantly worse results 30 min and 60 min after anaesthesia. The propofol group tended to be better than the isoflurane group, but the difference did not reach statistical significance. Also in the digit span, the scores were significantly lower 30 min after recovery from the anaesthetic. Here again the propofol group tended to be a little better than the isoflurane group 30 min, 60 min and 240 min after anaesthesia. In the Munich Verbal Learning Test both groups had lower scores 30 min and 60 min, the isoflurane group also 240 min, after recovery...