Early identification of those patients with fulminant hepatic liver failure (FHF) who need a transplant greatly helps in their management. A number of prognostic criteria have recently been proposed, including arterial blood lactate and serum phosphate concentrations. To validate their use, we retrospectively studied 83 consecutive patients with FHF admitted to our intensive treatment unit between August 2000 and March 2003. A total of 48 patients (58%) survived with medical management only (group I) and 35 patients (42%) failed to survive spontaneously (group II). This group included 19 patients (23%) who underwent orthotopic liver transplantation (LT), and 16 patients (19%) who died without undergoing LT (group IIa). A total of 5 patients (6%) who underwent liver transplantation died. Within paracetamol overdose (POD) and non-POD subgroups, phosphate concentrations were not significantly higher in group II patients (P = 0.08 and P = 0.27, respectively), when compared to group I patients. In multivariate analysis, post admission 12-hour lactate level was the only predictor of survival for the POD subgroup, whereas in non-POD patients, 12-hour lactate and admission bilirubin levels were significant in predicting patients' outcome. In conclusion, we found that while serum phosphate concentrations have limited clinical utility as prognostic markers, persistently elevated arterial blood lactate levels despite adequate fluid resuscitation are indicators of a poor prognosis in FHF. (Liver Transpl 2005;11:1073–1079.)