Hepatic lesions in 25 male and 24 female Syrian golden hamsters with N-Nitrosobis(2-oxopropyl)amine (BOP)-induced pancreatic cancer have been studied. Although BOP produced pancreatic cancer in 100% of the animals, its hepatocarcinogenic potential proved to be very weak, only occasional preneoplastic foci, neoplastic nodules and hepatocellular carcinoma developed. However, a broad spectrum of mainly proliferative, non-neoplastic alterations were found in the liver. The major site of alterations was the portal space, especially the biliary ducts were affected: bile duct hyperplasia, oval cell proliferation and formation of biliary cysts were the most frequently encountered changes. In the large ducts of the female hamsters a goblet cell metaplasia occurred, but the male animals were devoid of this lesion. Our results demonstrate that although the BOP is considered as a selective pancreatotropic nitrosamine derivate, it may cause various proliferative changes in the biliary duct system of hamsters.