['In some patients with severe exocrine pancreatic insufficiency, enzyme replacement therapy will not lead to clinical improvement or reduction of steatorrhea. Therefore, other mechanisms separately or in interplay with reduced enzyme secretion might be responsible for malabsorption in these patients.', 'To evaluate the prevalence of bacterial overgrowth, bile acid absorption capacity, and intestinal permeability in a group of patients with well-characterized exocrine pancreatic insufficiency.', 'Eleven men with severe exocrine pancreatic insufficiency, of whom 10 were receiving enzyme replacement therapy, were studied. The prevalence of bacterial overgrowth was evaluated by means of a hydrogen and methane breath test with glucose. Gamma camera scintigraphy after intake of 75Se-homocholic acid taurine (75Se-HCAT) was used to evaluate bile acid absorption capacity. Intestinal permeability was assessed from urine excretion of ingested 14C-mannitol and 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA), and these data were compared with results for 10 age-matched healthy men.', 'No patients had abnormal breath hydrogen or methane concentrations after glucose intake. Abdominal retention of 75Se-HCAT was reduced in three of the patients. The patients had lower urine excretion of 14C-mannitol than the control subjects, whereas no difference was revealed in urine excretion of 99mTc-DTPA.'] Is bile acid malabsorption or disturbed intestinal permeability in patients treated with enzyme substitution for exocrine pancreatic insufficiency caused by bacterial overgrowth?