Pure pancreatic juice was collected from 8 control subjects, 12 patients with chronic pancreatitis and 4 patients with cancer of the pancreas by endoscopic retrograde cannulation of the papilla. Samples were collected at 1 minute intervals for 20 minutes after rapid intravenous injection of secretin (Eisai, 1 U/kg) and for 10 minutes after rapid intravenous injection of CCK-PZ (Boots, 1 U/kg). Determinations of volume, bicarbonate concentration and three hydrolases (amylase, chymotrypsinogen and lipase) were made. Our tentative conclusions are (1) pancreatic enzymes are likely to be affected one after another, not in parallel fashing, in chronic pancreatitis and in cancer of the pancreas, (2) bicarbonate concentration and chymotrypsinogen or lipase are most susceptible in chronic pancreatitis and lipase secretion seems to be more susceptible than other parameters in cancer of the pancreas. Amylase is the least affected enzyme in both pancreatic diseases, and (3) determinations of chymotrypsinogen and/or lipase should be preferably performed among hydrolytic enzymes in the evaluation of exocrine pancreatic function in chronic pancreatitis and cancer of the pancreas.