Using Syrian golden hamsters, we studied the effect of pancreaticobiliary diversion (PBD) on plasma cholecystokinin (CCK) and exocrine pancreatic tissue over 5, 10, and 24 days. As compared with sham-operated controls, PBD-operated animals had increased plasma CCK concentrations by 228, 318, and 207% at 5, 10, and 24 days, respectively. Correspondingly, pancreatic wet weight increased by 24, 61, and 87%; total pancreatic protein by 6, 57, and 73%; and total pancreatic DNA by 35, 52, and 98%, respectively. At 5 days, but not at 10 and 24 days, there was a significant increase in the pancreatic tissue DNA concentration (p less than 0.01) and H-thymidine incorporation into DNA (p less than 0.02). Autoradiography showed increased H-thymidine labeling index in acinar cells at 5 and 10 days after PBD (p less than 0.01 and p less than 0.005). Although not significant, ductal cell labeling index was also increased at 5 and 10 days. These findings provide evidence that, as in the rat, PBD in the hamster induces hypercholecystokininemia with ensuing pancreatic hyperplasia and hypertrophy. The hamster model may be useful for studies on the effect of endogenous CCK on pancreatic ductal cell carcinogenesis and diseases of the gallbladder, neither of which can be studied in the rat.