The presence of K-ras point mutations in pancreatic duct carcinomas and cholangiocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine (BHP) in Syrian hamsters was investigated by single-strand conformation polymorphism analysis of polymerase chain reaction products from frozen fresh materials in order to clarify the K-ras mutation rates in those two carcinomas induced simultaneously by one carcinogen, BHP. In the examined pancreatic duct carcinomas, 10 out of 16 were positive for a mutation in codon 12 while 3 out of 12 cholangiocarcinomas demonstrated mutation of K-ras gene. G-to-A transition was detected in the second position of codon 12 in both pancreatic carcinomas and cholangiocarcinomas. These results suggest that the role of genetic alteration in carcinogenesis may differ with the target organ, even when initiation is with the same carcinogen.