This study was undertaken in order to ascertain the role of CA 19-9 in pancreatic cancer diagnosis. Therefore CA 19-9 was determined in the sera of 83 control subjects, 108 patients with pancreatic cancer, 112 with chronic pancreatitis and 126 with extrapancreatic diseases. Sensitivity, specificity and accuracy in detecting pancreatic cancer were: 75%, 86% and 61% respectively. The receiver-operating characteristic curves showed that CA 19-9 is able to well discriminate pancreatic cancer from controls; satisfactorily it differentiated pancreatic malignancy from chronic pancreatitis and other benign extrapancreatic diseases. Extrapancreatic neoplasms were not accurately separated. No difference was detected in CA 19-9 levels between pancreatic cancer patients with or without hepatic metastases. We can conclude that CA 19-9 is a test for pancreatic malignancy with a satisfactory sensitivity and specificity in respect of other pancreatic and extrapancreatic benign pathologies; the presence of hepatic metastases is only one of the factors which may increase its serum levels.