Fulminant hepatic failure is an important cause of morbidity and mortality in intensive care units. Conventional therapies are not sufficiently effective. Liver transplantation may be life saving, but a "bridge therapy" is needed until transplantation is performed. Hepatic extracorporeal xenohemodiafiltration (XHDF) is aimed at the transitory support of a patient with fulminant hepatic failure. The first clinical case of XHDF is presented. The system consisted of cross-circulation between a porcine liver and a patient with fulminant liver failure through a polyacrylonitrile membrane. The procedure lasted for 5 hours and produced hemodynamic, biochemical, and metabolic improvements. Intracranial pressure decreased from 34 to 5 cm H2O, serum ammonia fell from 673 to 370 ng/dl, lactic acid from 11 to 5.3 mmol/L, and bilirubin from 7.4 to 2.5 mg/dl. Hemodynamic values were maintained stable throughout the procedure. The patient was able to undergo transplantation and remains alive 11 months later. XHDF is a clinical experimental method that can constitute an alternative clinical therapy to support patients with fulminant hepatic failure until an organ is available for transplantation.