In view of forecasting the effect of octreotide acetate (Sandostatin) in preventing fistula formation after pancreatic surgery, 9 patients, who had pancreatoduodenectomy 8-12 days before, underwent a 2-day study. The first day, by means of a catheter located in the jejunal loop separately anastomosed to the pancreatic remnant, basal and after secretin stimulation pancreatic secretion was evaluated. During the 2nd day the possible inhibitory effect of octreotide on basal and stimulated secretion was investigated. Under the experimental conditions of the study Sandostatin showed little effect on the water and bicarbonate increase as stimulated by secretin. A greater hormone inhibitory effect on amylase production and pancreatic endocrine function was seen. On the basis of these results the use of Sandostatin can hardly be seen as useful in preventing fistula formation after pancreatic resection.