A chymotrypsin-like protease was detected along with elastase 1 in pancreatic secretion and stool. This enzyme was isolated from necrobiotic human pancreas, purified, partially characterized and designated as chymotrypsin B. Quantitative studies by rocket immunoelectrophoresis indicated that neither elastase 1 nor chymotrypsin B was degraded during intestinal passage. On the basis of a clinical study, both enzymes were found to reflect pancreatic function.