The known suppressive actions of glucagon on the secretion of pancreatic enzymes and of gastric acid, and the reported effectiveness of glucagon in treating acute pancreatitis, prompted the authors to carry out a prospective, randomized, double-blind, controlled trial of this hormone. Sixty-six patients with acute pancreatitis admitted to the surgical service of the Vancouver General Hospital were randomized into two groups of 33, receiving either glucagon or placebo in addition to their conventional therapy. The two groups were comparable with respect to the cause of the pancreatitis and the severity of the disease. Glucagon did not reduce the patients' analgesic requirements or the duration of abdominal signs, ileus, hyperamylasemia or hospital stay. Of the 66 patients, 4 died. Three of these were in the group receiving glucagon. The authors conclude that, contrary to theoretical expectations and the results of past uncontrolled trials, glucagon has no beneficial effect on the clinical course or outcome of acute pancreatitis, irrespective of the etiology or severity of the disease.