Subsequent to pancreato-duodenectomy with preservation of the pylorus in 12 patients the effect of parenteral and enteral nutrition on pancreatic secretion were compared. The pancreatic juice was continuously diverted from the Wirsung duct by nasopancreatic drainage. Postoperative feeding was administered by fine-needle catheter jejunostomy in 7 patients and 5 patients received total parenteral nutrition. The pancreatic juice was collected in four-hour fractions and it was analysed for volume, bicarbonate, protein, chymotrypsin and amylase. It has been found that on the first two days after the operation there was a slow increase in the measured values and on the third postoperative day after an abrupt rise the pancreatic secretion became steady. No differences in exocrine pancreatic secretion were observed between the enteral and parenteral methods of feeding. According to these data the two methods seem to be of the same value in the postoperative therapy.