The therapeutic efficacy of a pH-sensitive enteric coated pancreatic enzyme preparation was compared with conventional pancreatic enzyme preparations in 6 adult patients with exocrine pancreatic insufficiency. Fecal fat excretion and postprandial duodenal recovery of orally ingested pancreatic enzymes were evaluated after ingestion of each preparation. Fecal fat excretion decreased significantly (p less than 0.005) on treatment with pH-sensitive and conventional pancreatic enzyme preparations. Postprandial concentration and delivery of trypsin and lipase in samples aspirated from duodenojejunal junction were higher after ingestion of conventional pancreatic enzyme preparation as compared to the pH-sensitive enteric coated preparation. The difference, however, did not reach statistical significance. Our observations suggest that the pH-sensitive enteric coated pancreatic enzyme preparation is only as effective as conventional pancreatic enzyme preparations in controlling fat malabsorption in patients with exocrine pancreatic insufficiency. Failure of pH-sensitive enteric coated preparation to deliver greater quantities of pancreatic enzymes at duodenojejunal junction is most likely related to the impaired release of enzymes from microspheres due to low intraluminal pH in the upper small intestine in pancreatic insufficiency.