The NBT-PABA test, an oral pancreatic function test, was performed in 67 patients with proven chronic pancreatitis (secretin pancreozymin test or intraoperatively) and was pathological in 60 (89.6%). Prolongation of urinary collection period from 6 to 9 hours did not improve the diagnostic value. In comparison with the NBT-PABA test the sensitivity of trypsin and chymotrypsin determination in stool was 40.6% and 62.2%, respectively. In severe exocrine pancreatic insufficiency when pathological fecal fat excretion was demonstrable (steathorrhea) the accuracy of fecal enzyme determination was clearly higher (59.1% and 91.8%, respectively). Thus the NBT-PABA test is an alternative diagnostic tool for exocrine pancreatic insufficiency when the secretin-pancreozymin test, and fecal enzyme and fecal fat determination are too complicated. However, as intact absorption of NBT-PABA is possible, the test only provides a qualitative and limited quantitative evaluation of pancreatic function.