I syudied the relationship between aging and exocrine pancreatic function by endoscopic retrograde aspiration of pure pancreatic juice (PPJ). Control subjects consisted of 65 out-patients presenting mild vague abdominal aymptoms who fulfilled the following three criteria : 1) good general condition with no known organic diseaes ; 2) no abnormality in the live, bile duct, pancreas. kidney or metabolism ; 3) no alcohol consumption. Nineteen patients with definite pancreatitis were also studied. PPJ was collected form within the pancreatic duct by endoscopic retrograde catheterization of the papilla for 10 minutes after a bolus intravenous injection of secretion (Secrepan, Eisai co., Ltd., 100 U/bpdy). Exocrine pancreatic function was evaluated three parameters as fillows : secretory volume, maximal bicarbonate concentration or bicarbonate output, and enyme (amyase and lipase) output. The ordinary duodenal secretin test was also performed. Exocrine pancreatic function (both duct-cell and acinar-cell function) was significantly reduced in the elderly. The age-associated reduction showed a different pattern between duct-cell and acinar-cell function. The degree of duct-cell dysfunction was significantly higher than that of acinar-cell dysfuntion in the elderly. Influence of aging on maximal bicarbonate concentration was more clearly demonstrated by PPJ aspiration than by the ordinary secretin test. Elderly controls showed as much exocrine dysfuction as patients with chronic pancreatitis, making it difificult to diagnose chronic pancreatitis based on the exocrine function test alone. Therfore, clinical symptoms and findings as well as imaging tests should be considered for the correct diagnosis.