The examination of pO2, pCO2, lactate, pyruvate and glucose-concentration of arterial and brain venous blood shows significant differences only at 2. and 6. hours after operation between the 3 methods of general anesthesia, halothane-anaesthesia, neuroleptanalgesia and electrophypalgesia. The differences are related particularly to neuroleptanalgesia, which method directs the metabolic activity of the brain tissue to a more anaerobic state. Differences due to the age or to the personal factors of the patients were not seen.