A 15-year-old girl was found to have severe liver fibrosis on liver biopsy at the time of cholecystectomy, 5 1/2 years following a modified Fontan procedure (right atrial-right ventricular conduit) for tricuspid atresia. Postoperative right atrial pressures were consistently elevated above 13 mm Hg and this, in part, may have been due to progressive mild conduit stenosis. Because of increasing symptoms, the patient underwent successful revision of the conduit at the age of 15 years. It is suggested that sustained systemic venous hypertension caused the striking morphologic changes in the liver and that this serious complication may significantly affect the long-term prognosis of patients surviving the Fontan procedure.