In this study the Authors examine the usefulness in determining Fecal Chymotrypsin (FC) as a screening test for pancreatic exocrine insufficiency. The FC was measured in 503 children (337 control subjects and 166 with various intestinal and hepatobiliary diseases). The results demonstrate that FC is usefull as a screening test for pancreatic insufficiency. However, in certain cases, this should be supplemented by the more discriminant analysis of function provided by duodenal studies.