Five cases of the Budd-Chiari syndrome diagnosed by venography of the inferior vena cava, were studied on their obliterations, clinical course, laboratory data and angiographical findings. Obstructions of the inferior vena cava where the hpatic veins branched off were revealed in all cases. Membranes were present in the inferior vena cava in the hepatic portion in 4 of 5 cases, in 3 of which thromboses attached to their membranes. Another case showed a large thrombosis between hepatic veins and renal veins. Bilateral hepatic veins were not noted in 2 cases, nor singel hepatic vein in other 2 cases accompanied with the occulusion of the inferior vena cava. The rest case showed normal hepatic venography. Besides the common physical findings such as hepatomegaly, venous dilatation of abdominal wall and esophageal varices, venous dilatation of backs and both legs, and ulcers and/or pigmentations of both legs were observed in these cases and lead us to consider the Budd-Chiari syndrome. The remarkable abnomral retention of Bromosulfophthalein or Indocyanine-green, compared with slight dysfunction of the liver tests, supported the presence of this vascular disases. Three cases with large thromboses at the inferior vena cava showed typical clinical signs and symptoms as well as abnormal data of liver function tests, hematological examination, and renal function tests.