Patients with acute liver failure (ALF) have increased susceptibility to infections, principally as a result of impaired phagocytic function, reduced complement levels, and the need for invasive procedures. Bacteriologically proven infection is recorded in up to 80% of these patients and fungal infection (predominantly candidiasis) in 32%. Clinical signs such as high temperature and high WBC are absent in 30% of the cases. Pneumonia accounts for 50% of infective episodes, and bacteremia and urinary tract infection a further 20 to 25% each, at a median 5, 3, and 2 days, respectively, after the onset of ALF. Selective parenteral and enteral antisepsis regimens (SPEAR) were evaluated in prospective controlled studies, but early systemic antibiotics alone are as effective as SPEAR. With early antibiotics, the incidence of infective episodes is reduced to 20% and the overall mortality to 44%, with a reduction in progression to encephalopathy and an increased opportunity for transplantation.