We studied the clinical significance of serum Gc levels in the sera of patients with acute hepatic necrosis. Gc concentration were measured using an EIA in double sandwich technique with purified Gc as standard. Mean levels of serum Gc were 6.0 +/- 7.4 mg/dl in fulminant hepatitis, 20.8 +/- 13.6 mg/dl in acute hepatitis and 39.4 +/- 13.8 mg/dl in normal subjects respectively. There was slight correlation between Gc and PTT (P less than 0.05). In the observation of sequential study in patients with fulminant hepatitis, serum Gc levels of live cases elevated but those of dead cases slightly elevated, thereafter decreased. These results suggested that serum Gc levels was the useful marker as a grade of liver cell damage and a parameter of regeneration in liver cells.