Fifty hepatic occlusive venograms with the Swan-Ganz balloon catheter were obtained in 20 patients with portal hypertension. The venographic patterns of hepatic veins were divided into four categories: (a) hepatic venous system without visible alterations; (b) slight loss of branching and tapering, no major wall irregularities; (c) considerable loss of branching and tapering and/or marked wall irregularities; and (d) severe reduction of venous tree with severe wall irregularities ("defoliated tree"). These correlated with severity of the disease. The portal venous system was simultaneously opacified in 10 patients. Intrahepatic and extrahepatic collaterals were found in 8. Hepatic occlusion venography is a suitable method for evaluating alterations of the liver outflow tract in portal hypertension.