To confirm correlation between function and histology of the exocrine pancreas in chronic pancreatitis, we compared exocrine pancreatic function, as estimated by cholecystokinin secretin test (CST), with histological findings in 108 patients. Exocrine pancreatic insufficiency was graded from 0 to 4 according to the number of abnormal CST parameters. Histological findings also were graded from 0 to 4. Results of CST in 108 patients were normal (grade 0) in 52, equivocal (grade 1) in 23, and abnormal (grades 2-4) in 33. Normal histological findings (grade 0) were observed in 54 patients, equivocal (grade 1) in 15, and abnormal (grades 2-4) in 39. We confirmed that there was a significant correlation between histological grading and overall scoring (tau = 0.59, p less than 0.01) or individual parameters (tau = -0.36 for volume, -0.45 for amylase output, and -0.54 for maximal bicarbonate concentration (p less than 0.01) of CST. Sensitivity of CST was 67% in 39 patients with histologically confirmed chronic pancreatitis, specificity was 90% in 69 patients without chronic pancreatitis, based on histological evidence, and efficiency was 81%. In conclusion, we confirmed a highly significant correlation between direct function test (CST) and histology of the exocrine pancreas.