Traditional methods for collecting duodenal fluid are time consuming and technically difficult. A simple endoscopic method is proposed in this report as a means of collecting duodenal fluid to perform exocrine pancreatic function tests. Thirty-five patients between 24 and 36 months of age were studied for pancreatic exocrine function. Twenty-seven presented with chronic diarrhea and 8 with failure to thrive. In 20 patients (group 1), duodenal fluid was collected by means of a double-lumen tube and sequential administration of pancreozymin (PZN) and secretin (SEC). The rest (group 2) had duodenal aspiration from the level of the papilla of Vater through a fiberoptic endoscope following administration of SEC only. The procedure took approximately 3 h in group 1 and 45 min in group 2. Secretin administration produced comparable levels of enzymes in both groups. Pancreozymin produced the highest enzyme levels, but this was only significantly higher than SEC-induced levels in the case of lipase. Endoscopic collection of duodenal fluid following SEC administration is a safe, quick, and reliable method of collecting pancreatic secretion.