Serum amylase and lipase concentrations were determined in 78 patients with chronic liver diseases [26 chronic active hepatitis (CAH) and 52 liver cirrhosis] and in 15 healthy subjects. Pancreatic isoamylase concentrations and macroamylase complexes were assayed in hyperamylasemic sera. Serum amylase levels were abnormally elevated in 27 patients (35%; 22 liver cirrhosis, 5 CAH), whereas serum lipase levels were elevated in 16 patients (21%; 15 liver cirrhosis, 1 CAH). In 9 of the 27 hyperamylasemic patients, the hyperamylasemia was of pancreatic type. Macroamylasemic complexes were not detected in hyperamylasemic sera. Patients with liver cirrhosis had serum levels of amylase and lipase significantly higher than both the healthy subjects and the patients with CAH, while no significant differences were found in serum levels of these enzymes in patients with CAH as compared to the healthy subjects. A decreased liver metabolism of serum amylase and lipase in patients with chronic infective liver disease, especially in those having liver cirrhosis, may lead to an accumulation of these enzymes in the blood.