Hepatic inflow occlusion was applied to five pigs for 15 min. Splanchnic congestion was avoided by a temporary portacaval anastomosis. Different coagulation factors were determined during and after the hepatic ischaemia. Transient increase in recalcification time and in partial thromboplastin time in siliconized glass and in untreated glass were found during the occlusion in two pigs and shortly after re-establishment of the circulation in two others. No pronounced changes in coagulation factors were noted. The possibility of a transient increase in anticoagulating substances, which might be due to either a release from the liver or a decreased clearing in the liver of anticoagulating substances during and after the ischaemic period, is discussed.