Histological differentiation between chronic pancreatitis and pancreatic cancer, especially in biopsy material, remains challenging and the frequent association of 'secondary' chronic pancreatitis (due to ductal obstruction) with pancreatic cancer causes additional diagnostic problems. Our study, using anti-ErbB2 antibodies from Santa Cruz and Dako in tissues from the normal pancreas, chronic pancreatitis and pancreatic cancer showed that these antibodies discriminate between primary chronic pancreatitis and 'secondary' chronic pancreatitis due to pancreatic cancer. Tissues from 28 pancreatic cancer patients, 15 chronic pancreatitis patients and 12 organ donors or early autopsy cases were subjected to immunohistochemical studies using polyclonal ErbB2 antibodies from Santa Cruz and Dako. The Santa Cruz antibody immunoreacted with islet cells in all tissues from the normal pancreas and pancreatic cancer but not in any chronic pancreatitis specimen. The Dako antibody showed a membrane staining of ductal and ductular cells only in chronic pancreatitis cases but in none of the normal or cancer specimens. Moreover, in chronic pancreatitis cases, ductular cells were stained with the Santa Cruz antibody only in the severe form, but not in the mild or moderate form of the disease. The utilized ErbB2 antibodies discriminate between the normal pancreas, chronic pancreatitis and pancreatic cancer. Hence, these antibodies seem to present an additional useful aid in the surgical pathology of pancreatic diseases.