Abstract： Objective To investigate the relationship of pancreatic exocrine function with the pancreatic cancer staging and the size of tumor. Methods N-benzoyl-tryrosyl para-aminobenzoic acid (NBT- PABA) test was used to measure the pancreatic exocrine function of 39 pancreatic cancer patients, 46 chronic pancreatitis patients and 20 normal subjects. In pancreatic cancer group, the relationship of pancreatic exocrine function with the size of tumor (TS) and JPS classification (T factor) was analysed. Results The rate of NBT-PABA excretion in normal subjects, chronic pancreatitis patients were (78.9±15.9)%, (58.6± 19.3)%, respectively; in mild, moderate, severe chronic pancreatitis patients, the values of NBT-PABA were (75.5±23.6)%, (57.9±21.5)%, (45.5±16.7)% ; respectively. The rate of NBT-PABA excretion in pancreatic cancer patients was (47.6±18.3)%, and the rate of NBT-PABA excretion in patients with T3+T4 stage was (42.2±21.70%, and was obviously less than (64.8±11.2)% of T1+T2 stage (P<0.05). Tthe rate of NBT-PABA excretion in patients with TS3+TS4 was (34.8±17.2)%, and was significantly lower than (55.6±23.5)% of TS1+TS2(P<0.05). The rate of NBT-PABA excretion in patients with pancreatic head cancer was (42.5±16.4)%, which was significantly lower than (71.8±9.6)% of the pancreatic body and tail (P<0.05). In the 33 patients with pancreatic head cancer, the rate of NBT-PABA excretion in patients with main pancreatic duct stricture was (54.2±14.1) %, which was significantly higher than (37.6± 14.1)% of patients with main pancreatic duct interruption (P<0.05). There was no significant difference in pancreatic exocrine function between pancreatic cancer and moderate or severe chronic pancreatitis.Conclusions The pancreatic exocrine function was related to the pancreatic cancer staging and the size of tumor to some degree,but it was affected by mass location,and it was also affected by degrees of the pancreatic duct obstruction. The pancreatic exocrine function can not be used to differentiate pancreatic cancer from moderate or severe chronic pancreatitis.