The pathogenesis of congestive cirrhosis is generally thought to be a reaction of the hepatic stroma to hypoxia, pressure, or necrosis. This does not explain the poor correlation between symptoms and severity of fibrosis and the irregular distribution of fibrosis within the liver. We have observed healed hepatic vein (HV) thrombosis in patients with congestive heart failure (CHF). The purposes of this study were to document hepatic vascular lesions in autopsy livers of patients with chronic CHF, to determine the role of these lesions in the pathogenesis of congestive cirrhosis, and to refine the definition of congestive cirrhosis. Twenty-five livers were studied, 13 with multiple large blocks 4 x 5 cm. Sections were graded for parenchymal fibrous septa, sinusoidal fibrosis, and intimal fibrosis of portal veins (PVs) and HVs. Fibrous septa were found in livers of 7 of 13 patients with CHF and in none of' 12 controls without CHF (P = .007). Parenchymal fibrosis was highly variable in distribution, often with severe septation in some areas and nearly normal morphology in others. Intimal fibrosis and obstruction of small-and medium-HVs were found only in livers of patients with CHF. The vascular lesions were confined to regions with fibrous septation and had morphology suggestive of organized thrombosis. Acute thrombi in sinusoids were noted in livers of 4 patients with CHF and in livers of 2 patients without CHF. These findings support the hypothesis that congestive cirrhosis is a response to intrahepatic thrombosis. The pattern of disease suggests that thrombus begins in sinusoids, occasionally propagates to HVs, and causes secondary local PV thrombosis, ischemia, parenchymal extinction, and fibrosis. (HEP.4TOLOGY 1995;21: 1232-1237.) Hepatic fibrosis is found in the majority of patients with prolonged congestive heart failure (CHF 1. Congestive hepatic fibrosis varies from a mild deposition of sinusoidal collagen to broad fibrous septa with distor-Ahhreviations: CHF, congestive heart failure; HV, hepatic vein; PV, portal From the Deparlmenl of Pathology, The Toronto Hospital and the Canadian