N-nitrosobis(2-oxopropyl)amine (BOP)-induced pancreatic ductal carcinomas and early ductal lesions in Syrian hamsters have been reported to show histopathological resemblance to those in humans. Specific protein expression profiles have been found in human carcinomas, but a detailed molecular approach regarding the dissection of BOP-induced pancreatic carcinogenesis has yet to be determined. The present immunohistochemical study of early and advanced hamster lesions focused on five proteins reported to be overexpressed in human patients, to clarify interspecies phenotype similarity. Integrin α(V)β(3) was found to be overexpressed in the epithelial cells of 13 of 14 atypical hyperplasias and 6 of 6 adenocarcinomas. This overexpression was more frequent than in the remaining four proteins. However, immunoreactivity for α-enolase in epithelial cells and for kallikrein 7 and galectin-1/3 in both epithelial and stromal cells was also evident at various frequencies. Thus, similarities of tumor-associated protein expression between human and hamster pancreatic ductal lesions were confirmed, and integrin α(V)β(3) was identified as a potentially useful immunohistochemical marker for early lesions in hamsters.