In 1877, von G. W. Eck made an anastomosis between the portal vein and vena cava inferior and by ligating the upper part of the portal system, the portal blood was transferred to the vena cava inferior. This method of so-called Eck's fistula was thereafter further studied and improved on by many authorities. Above all, the method which is used “three bladed clamp forceps” after Jeger, Horsley, or Yabuki, etc., is generally brought into practice nowadays, as it is the most non-dangerous, however, the result of the operation is either in failure or unsatisfactory unless a large animal which possesses some large blood-vessels is employed. The new method established by the author is well improved on and can be applied even to such animal as rabbit which possesses relatively small blood-vessels. Turning my attention that it is very convenient to use the simple forceps which has no middle blade, I reformed the “Hernio-clamp-forceps” to make use of compressing arteries. The whole length of the forceps and its blade-length measure 18cm, and 8cm, respectively. It curves to a crescent-shape and the portion 3cm long, near the point is defaced on its curved face, making the blade-thickness to 0.1cm. This defaced portion is of use to compress together the portal vein and the vena cava inferior which are to be communicated. By using this clamp-forceps it was ascertained that the blood-vessels which measure only 0.4cm, diameter also can be anastomosed without closuring their circulation of the blood. The process of the new method is quite similar as before until it reaches to the vena cava inferior and the portal vein and firstly, the portal vein is caught with a ligature by inducing of an anuerysm-needle at the first branch of the porta hepatis, it is prepared for the subsequent ligation. Secondly, for the vena cava inferior, the hepatorenal ligament is separated and pressed the liver as much as possible and a ligature is caught to this vein, coinciding with the above loop of ligature of the portal vein. Both the blood-vessels are peeled their tunica adventitia at the anastomosed region and the two ligatures above mentioned are softly and carefully pulled by an assistant and let the both blood-vessels bring in contact with. The operator fixes horizontally the two blood-vessels with forceps and compresses them together, keeping the circulation of the blood of portal vein. On this ocassion, it must be careful not to pinch the ligature or the adjacent tissues. As the two blood-vessels are kept horizontally, the circulation of the blood of the large vena cave inferior is not interfered. Next, at the region where the tunica adventitia is peeled a certain longitudinal section is done and an anastomosis in situ is followed by a running suture. By this method, not only the operation on dog is easily performed but also it is well applied on small animal such as rabbit which was hitherto considered to be very difficult. However, on rabbit as its blood-vessels are very small and at the same time their walls are also very thin, it is frequently very hard to perform the anastomosis, keeping the circulation of the blood.