The pancreatic function diagnostant (PFD test) and fecal chymotrypsin test were performed simultaneously in patients after pancreatic surgery, and findings for both tests were analyzed. The p-aminobenzoic acid recovery rate in the PFD test and the chymotrypsin activity in stools decreased after pancreatectomy, particularly after extended radical pancreaticoduodenectomy. Chymotrypsin activity in stools, measured by the fecal chymotrypsin test after extended radical pancreaticoduodenectomy, was significantly lower than the normal level. The D-xylose output in the extended radical group was significantly (p<0.05) lower than that following conventional pancreaticoduodenectomy. The results allow the conclusion that the absorption factor must be taken into account when evaluating the pancreatic exocrine function by the PFD test.