Experiments with Wistar rats have been performed in order to analyse brain and liver metabolism after suturing of the rats right carotid artery. It should be figured out how much an interruption of the bilateral blood supply of the brain during end-to-end-anastomosis of a carotid artery would interfere with normal brain and liver metabolism. General anaesthesia of all animals was obtained with pentobarbital. The vascular anastomoses have been performed by using the microsurgical technique. Groups of animals were formed in order to analyse metabolism after various periods of postoperative survival. Brain and liver tissue was removed and the metabolism stopped immediately by freezing the tissue in liquid nitrogen. Biochemical analysis showed several highly significant changes of levels of values indicating hypoxia. Additional experiments have been carried out in order to find out whether hypoxia could be detected in other organs of the body such as the liver after performing the same microsurgical procedure on a carotid artery and how pronounced these changes would be compared to those of brain metabolism. Results of experiments performed up to now indicate that hypoxia also develops in liver tissue.