Liver affects the release and clearance of many hormones, but the interactions between gastrointestinal peptides and liver function are obscure. Aim of this study was to evaluate plasma concentrations of gastrointestinal peptides during acute hepatic cytonecrosis and during liver regeneration in man. The study was performed in ten patients with viral hepatitis (8 virus A, 2 virus B) in the acute phase (alanine transaminase = 3073 +/- 739 U/L; mean +/- SEM), and at days 7, 45 and 52 after the initial evaluation, during clinical and biochemical recovery (52nd day, alanine transaminase = 77 +/- 26). Plasma concentrations of the following hormones were evaluated by radioimmunoassay: glucagon, insulin, gastrin, vasoactive intestinal peptide, bombesin, neurotensin, cholecystokinin, secretin and motilin. Only serum bombesin and cholecystokinin were significantly (p < 0.01) increased in the acute phase of hepatitis (bombesin: 138 +/- 21 pg/ml; cholecystokinin: 57 +/- 7 pg/ml); they returned to normal values during convalescence (bombesin: 60 +/- 8; cholecystokinin: 31 +/- 4). During hepatocellular necrosis, plasma concentrations of cholecystokinin and bombesin, which are both cellular growth factors and regulatory signals of food introduction and satiety state, were increased by 83% and 130%, respectively. Increase of these hormones may cause the dyspepsia and lack of appetite that characterizes the initial phase of acute viral hepatitis.