Measurement of the pancreatic exocrine secretion was performed for 20 minutes using a gastrofiberscope. The exocrine pancreas was stimulated by 1 clin. U./kg secretin and 40 ng/kg caerulein as a bolus injection. Aspiration of duodenal juice was performed by a polyaethylen-tube through the biopsy-channel of the endoscope while duodenum distal of the papilla was shut by a baloon-tube, fixed on the distal end of the gastrofiberscope. In 84 patients the investigation was done 87 times. In 11 cases of proved chronic pancreatitis the endoscopic secretin-caerulein-test (SCKT) was pathologic in each case. --Normal values obtained by SCKT were in the range of those obtained by standard secretin-pancreozymin-test with correction of the volume of duodenal juice. Maximal enzyme output was always found in the first five-minute fraction of duodenal juice. Maximal bicarbonate output was found later between 15 and 20 minutes after stimulation. There was a good correlation between maximal enzyme output and maximal bicarbonate output in SCKT on one side and the results of a standard secretin-pancreozymin-test later performed in the same 10 patients. The SCKT is an easy and fast practicable method to be done after routine gastroscopy.