A retrospective multi-institutional study was carried out on a series of 38 patients with histologically proved Budd-Chiari syndrome: Five patients had acute disease, and 33 had subacute or chronic disease. All patients underwent dynamic CT scanning. Angiography was performed in 20 cases, inferior cavography in 22, and wedge-hepatic venography in 16. In all acute cases, CT showed global liver enlargement with diffuse hypodensity on plain scans and patchy enhancement after contrast material injection. Thrombosis of the three main hepatic veins was always demonstrated. In subacute or chronic disease, plain CT scans showed abnormalities of liver morphology and hypodensity either in atrophic areas (19 cases) or in the periphery of the liver (eight cases). With dynamic CT, patchy enhancement was present in 28 cases. Correlation with angiography in 15 cases revealed a normal portal blood flow in enhanced areas and an inversed portal blood flow in atrophic areas. Different morphologic and enhancement patterns on CT scans could be related to the direction of portal blood flow, which changes with different stages of Budd-Chiari syndrome.