The expression of mRNA for epidermal growth factor (EGF), transforming growth factor-α (TGF-α), EGF receptor (EGFR) and e-erbB-2 genes and the immunoreactivity to these gene products were examined in 3 newly established humand panereatic carcinoma cell lines and their corresponding in vivotumor lines using the Northem blot technique and the immunohistochemical method. All 3 cell lines expressed TGF-α, EGFR and 2 of the 3 lines expressed EGF and c-erbB-2mRNAs. The immunohisochemical study showed immunore-acvitity to EGF, TGF-α and EGFR in all these 3 cell lines and their corresponding vivo tuor lines. These results indicate that the autocrine loop of EGF and /or TGF-α/EGFR in pancreatic carcinoma cells may be one of the important reasons for the uncontrolled growth of the pancreatic carcinoma. The c-erbB-2 overexpression in some of the cell lines may slao contribute to the carcinogenesis or progression of this cancer.