Exocrine pancreatic function was studied by rapid intravenous injection and by prolonged intravenous infusion of a combination of secretin and caerulein in a group of patients with proven pancreatic disease and in controls. The aim was to compare the value of the two procedures of stimulation in the diagnosis of exocrine pancreatic insufficiency. Results showed that the pancreatic response to infusion of the stimulants discriminates normal from abnormal pancreatic function better than responses to rapid injection.