['Measurement of faecal elastase (FE1) is used widely to screen for pancreatic exocrine insufficiency (PI). FE1 does not allow differentiation of primary from secondary PI.', 'To investigate the relation between duodenal morphology and FE1 in children with secondary PI resulting from primary gastrointestinal diseases.', 'A group of 51 children underwent small intestinal biopsy and FE1 measurement. Villus to crypt ratio (VCR) and inflammation within the lamina propria of duodenal mucosal biopsy specimens were scored and compared with FE1 values.', 'In 51 children from nine diagnostic categories, a highly significant correlation between FE1 and both duodenal morphology and inflammation was found.'] Is faecal elastase 1 concentration a marker of duodenal enteropathy?