A modified secretin-pancreozymin test was performed for the quantitative determination of both the pancreatic exocrine function and the biliary secretion of total bile acids followed by exogenous (secretin and pancreozymin) and endogenous (L-phenylalanine) stimulation of the pancreatic and biliary secretion. The outputs of lipase, alpha-amylase, trypsin, bicarbonate and total bile acids were estimated and the ratio of glycine to taurine conjugated bile acids was measured by thin layer chromatography. Polyethylene glycol 4,000 was used as a nonabsorbable marker for the correction of aspirated volumes. 40 patients were studied: 10 control subjects; 10 control subjects with previous cholecystectomy; 10 patients with chronic pancreatitis and 10 cholecystectomized patients with chronic pancreatitis. In cholecystectomized probands, not only the total bile acid output but also the output of bicarbonate, trypsin and lipase were diminished compared to the control subjects with a intact gallbladder. In noncholecystectomized and cholecystectomized patients with chronic pancreatitis both, the pancreatic secretion and the biliary bile acid secretion were significantly decreased. The ratio of glycine/taurine conjugated bile acids was found to be significantly higher in these patients compared to the controls.