In the previous studies, we found that endurance training increased pancreatic weight, protein content, and enzyme activity with hypertrophied acinar cells in rats. The purpose of the present study was to investigate the effect of endurance training on pancreatic exocrine response to CCK in rats. Female F344 rats were divided into control (C, n=6) and endurance training (T, n=6) groups. The trained rats were exercised for 60 min on a treadmill (final speed, 35 m/min), 5 days a week, for 8 weeks. Food intake in both groups was matched. On the final day of the experiment, the rats were anesthetized after an overnight fast and prepared with cannulae into the pancreatic duct. After 1-h basal collection with 0.9% NaCl (7.5 ml/kg body weight/h) injected intravenously, CCK-8 (0.06μg/kg body weight/h) was injected intravenously and pancreatic secretions were collected for the additional three 1-h periods. Final body weight in the T group was slightly, but not significantly, lower than in the C group (C : 145±6, T : 137±8 g). Pancreatic wet weight in the T group was significantly higher than in the C group (C : 4.14±0.16, T : 4.71±0.18 mg/g BW). CCK-stimulated pancreatic juice secretion was not significantly changed. There were significant increases in pancreatic protein and amylase secretions with CCK administration. CCK-stimulated pancreatic protein and amylase secretions were significant higher in the T group than in the C group. Total pancreatic protein secretion with CCK administration during 3 hours were significant higher in the T group than in the C group (C : 2.52±1.92, T : 5.11±1.50 mg/3 h). Total amylase secretion with CCK administration during 3 hours were also significant higher in the T group than in the C group (C : 0.69±0.43, T : 1.12±0.37 U/3 h). These results suggest that the endurance training increased pancreatic exocrine secretion response to CCK. CCK may play an important role in exercise-induced enhancement of the exocrine pancreas.