The authors describe four patients with Budd-Chiari syndrome in whom contrast material-enhanced computed tomographic (CT) scans demonstrated low-density venous thrombosis in three sites not, to our knowledge, previously described with this modality. Thrombosis was seen in the portal circulation, the hepatic veins, and the intrahepatic inferior vena cava. It is known that concomitant portal vein thrombosis may be seen in 20% of patients with Budd-Chiari syndrome. Three of the four patients in the current study had this finding, one with extensive thrombosis of portal, mesenteric, and splenic veins and the other two with portal vein branch involvement. In one patient hepatic vein thrombosis was demonstrated with CT, and in three inferior vena cava clot was demonstrated. All four patients had the distinctive hepatic parenchymal contrast enhancement pattern seen in this condition, which the authors think may be at least partially caused by associated portal thrombosis. The presence of portal venous thrombosis should prompt the observer to consider the diagnosis of Budd-Chiari syndrome. Detection of hepatic vein clot confirms the diagnosis and may be seen in this condition in association with inferior vena cava thrombus.