The model of temporary complete liver ischemia was investigated in 60 pigs in order to produce a disease which resembles liver failure in man. The interval of time leading to death in every animal differed in a wide range. A number of biochemical alterations was of no value as for the prognosis of the animal under investigation. The ammonium in the peripheral blood is elevated during shunting of portal blood around the liver only. Microscopic examinations demonstrated that the damage produced is limited to the hepatic tissue. The lesions were less when ischemia was produced after a longer interval after the operation. The role of processes of regeneration and reparation of liver tissue is discussed.