This report is concerned with studies on exocrine function and it's corelation with endoscopic retrograde cholangiopancreatography in cases of choledocholithiasis and cholelithiasis. Following are the results obtained. 1) Pancreozymin-Secretin test showed a decrease of exocrine function, in 53.3 percent of choledocholithiasis and in 26.9 percent of cholelithiasis. However, when the results were evaluated by physiological values of individual patient's age group, the corrected incidence was 20 percent and 7.7 percent respectively. 2) Most frequently observed abnormality was a decrease in maximal bicarbonate concentration. However, when the results were evaluated by physiological values of individual patient's age group, incidence of a decrease was similar in four factors; volume, maximal bicarbonate concentration, total bicarbonate out put, and total amylase out put. 3) No abnormality of exocrine function test was observed in cases with normal ERCP, whereas abnormal ERCP does not necessarily indicate a normal exocrine function. Decrease in exocrine function is expected in 70 to 75 percent of cases with moderate to marked dilation and irregularity of the margin and diameter of the pancreatic duct. 4) Results of the present and the previous report indicate the following process as the most likely pathogenesis of chronic pancreatopathy associated with diseases of the biliary tract; diseases of the biliary tract→ abnormality of the Vaterian pancreatic and bile duct→ obstruction of outflow of pancreatic juice→ dilatation and other abnormalities of the pancreatic duct→ chronic pancreatopathy. 5) In conclusion, diagnoses and treatment of cholelithiasis and choledocholithiasis can be satisfactory only with concomitant evaluation and treatment of abnormalities of the Vaterian bile and pancreatic duct and the pancreas.