Viral hepatitis is the commonest cause of fulminant hepatic failure (FHF) in developing countries. We evaluated the early indicators of prognosis in these patients by multivariate analysis. The records of 204 consecutive patients with acute liver failure admitted with hepatic encephalopathy over five years were studied. The etiology of these patients included virus related in 186 (91.1%), drug induced in 15 (7.4%), Wilson's disease in one (0.5%), acute Budd-Chiari syndrome in one (0.5%), and malignant infiltration in one (0.5%). Patients with FHF complicating viral hepatitis were analyzed by univariate and multivariate analysis. These patients were further subclassified depending upon the interval between the onset of jaundice and the onset of encephalopathy into hyperacute (HALF; interval 0-7 days), acute (ALF; interval 8-28 days) and subacute liver failure (SALF; interval 4-12 weeks). Sixty (32.3%) patients with viral hepatitis survived. Univariate analysis showed that the interval between onset of encephalopathy and onset of jaundice, grade of encephalopathy, raised intracranial pressure, prothrombin time, and serum bilirubin levels on admission were related to outcome in these patients. Multivariate logistic regression analysis showed that the presence of raised intracranial pressure at the time of admission, prothrombin time >100 sec on admission, age (>50 yr), and onset of encephalopathy seven days after onset of jaundice were associated with poor prognosis. Forty seven (37.0%) of 129 patients with HALF survived compared with 9 (22.5%) of 40 with ALF and 4 (21.1%) of 19 with SALF (P = NS). Raised intracranial pressure was more frequent in patients with HALF (48.8%) than in patients with ALF (32.5%) and SALF (15.8%; P = 0.01), while clinically detectable ascites was more frequent in patients with SALF (78.9%) compared with HALF (19.7%) and ALF (37.5%; P < 0.0001). The factors adversely affecting the outcome in our patients with FHF complicating viral hepatitis include presence of overt clinical features of raised ICP at the time of hospitalization, prothrombin time (>100 sec) on admission, age (>50 yr), and onset of encephalopathy seven days after onset of jaundice.