Background: The failing Fontan circulation is associated with hepatic impairment. The nature of this liver injury is poorly defined. Objective: To establish the gross and histological liver changes of patients with Fontan circulation relative to clinical, biochemical and haemodynamic findings. Methods: Patients were retrospectively assessed for extracardiac Fontan conversion between September 2003 and June 2005, according to an established clinical protocol. Twelve patients, mean age 24.6 ( range 15.8-43.4) years were identified. The mean duration since the initial Fontan procedure was 14.1 ( range 6.9-26.4) years. Results: Zonal enhancement of the liver (4/12) on CT was more common in patients with lower hepatic vein pressures (p=0.007), and in those with absent cardiac cirrhosis on histological examination (p=0.033). Gastro-oesophageal varices (4/12) were more common in patients with higher hepatic vein pressure ( 21 (6.3) vs 12.2 (2.2) mm Hg, p=0.013) and associated with more advanced cirrhosis (p=0.037). The extent of cirrhosis (7/12) was positively correlated with the hepatic vein pressure (r=0.83, p=0.003). A significant positive correlation was found between the Fontan duration and the degree of hepatic fibrosis (r=0.75, p=0.013), as well as presence of broad scars (r=0.71, p=0.021). Protein-losing enteropathy (5/12) occurred more frequently in patients with longer Fontan duration (11.7 (3.2) vs 17.9 (6.1) years, p=0.038). Conclusions: Liver injury, which can be extensive in this patient group, is related to Fontan duration and hepatic vein pressures. CT scan assists non-invasive assessment. Cardiac cirrhosis with the risk of developing gastro-oesophageal varices and regenerative liver nodules, a precursor to hepatocellular carcinoma, is common in this patient group.