A cooperative study was conducted to determine the efficacy of one week of treatment with infusion of 1 mg glucagon and 10 units insulin twice daily in severe acute hepatitis. Ninty-eight patients with either prothrombin time less than 60% or thrombotest or hepaplastin test less than 50% of normal were randomly assigned to hormone or placebo treatment. SGOT and SGPT values dropped after treatment with a gradual decrease or increase in total serum bilirubin or cholesterol levels similarly in both groups receiving hormone or placebo. Deranged prothrombin time improved more rapidly in the hormone group than in the placebo group. Glucagon and insulin infusion may stimulate recovery of the liver from injury.