Serial hepatic volumetry calculated from the liver area on abdominal computed tomography was performed in 19 patients with fulminant hepatic failure to determine a relationship between liver volume and prognosis. All patients received intensified artificial liver support comprised of plasma exchange and hemodiafiltration using high-performance membranes, and 10 patients survived. Liver volume was significantly larger in survivors than in nonsurvivors, both in an initial volumetry performed at the onset of coma and in subsequent volumetry performed 10-20 days after the onset of coma. The difference became more significant in the subsequent volumetry because of the recovery of liver size in some of the survivors and progressive liver shrinkage in all nonsurvivors. All patients with a liver volume greater than 656 ml at 10-20 days after the onset of coma survived, whereas all but one patient with a liver volume less than that died. Multivariate analysis revealed only liver volume in subsequent volumetry had discriminatory power upon prognosis among six prognostic factors. These observations imply that in order to obtain an accurate prediction of fulminant hepatic failure by hepatic volumetry, serial studies at least until 10-20 days after the onset of coma are necessary.