Because cholecystectomy stimulates hypertrophy and hyperplasia in the hamster pancreas, its effect on experimental pancreatic carcinogenesis was studied in this animal model. Forty female Syrian hamsters underwent cholecystectomy, while 40 others underwent sham operations. Two weeks later, 30 hamsters undergoing cholecystectomy and 30 hamsters undergoing sham operations received 4 weekly subcutaneous injections of N-nitroso-bis (2-oxopropyl) amine (BOP) (10 mg/kg). Remaining hamsters (n = 20) received equal volumes of 0.9% saline solution. A further 10 hamsters (controls) underwent no surgery and received no injections. Thirty weeks after the first BOP or saline injection the pancreas of hamsters that had undergone cholecystectomy was only 3% heavier than that of sham-operated animals, and there was no difference in the incidence of pancreatic cancer between BOP-treated hamsters that had undergone cholecystectomy and those that had undergone sham operations. In this study, cholecystectomy had no influence on BOP-induced pancreatic carcinogenesis in the Syrian hamster.