We examined the morphological and haemodynamic changes in the livers of rats following acute obstruction of portal vein branches by the injection of agar into the portal vein. Histological and angiographic examinations of the liver were performed after measurements of portal vein pressure in vivo and portal vascular resistance by an isolated liver perfusion method. Portal vein embolism induced hepatic necrosis in the centrilobular and midzonal areas, which was rapidly resorbed and replaced by regenerated liver cells leaving no trace. This recovery from hepatic necrosis was closely related to recanalization of obstructed portal vein branches, which led to falls in both the elevated portal vein pressure and the increased portal vascular resistance following embolization.