The concentration of trypsin, pancreatic iso-amylase, phospholipase, and lipase were determined in intestinal content during the first two hours of digestion of a test meal. In normal subjects the concentration curves for all enzymes displayed a typical biphasic pattern. In patients with chronic pancreatic disease, the typical variations of the enzyme concentrations were markedly diminished. In patients with celiac disease, the initial peak of the trypsin and phospholipase activities seemed to be delayed, and in patients operated upon with a Polya gastric resection the concentrations of trypsin and phospholipase increased gradually. In these two disorders the lipase concentration curve was of quite a different, uncharacteristic pattern. It is suggested that the concentration curves of the enzymes reflect pancreatic secretion. Furthermore, the secretion of lipase in celiac disease and following gastric resection seems to be 'non-parallel'. Owing to a fairly considerable variation in the values from different individuals, it seems reasonable to conclude that in clinical practice determination of enzyme concentration curves after a test meal probably does not improve the reliability of the conventional Lundh test.