Serum CA 19-9 was determined in 83 control subjects, 99 patients with pancreatic cancer, 104 with chronic pancreatitis and 137 with extra-pancreatic diseases mainly of gastrointestinal origin in order to evaluate whether hepatic factors can influence circulating CA 19-9 in pancreatic cancer. Sensitivity, specificity and accuracy of this test in determining pancreatic malignancy were: 74%, 83% and 57%. We divided patients into two groups: group A (159 cases) and group B (181 cases) with and without anatomical liver damage (presence of primary or metastatic cancer, cirrhosis, hepatitis, steatofibrosis, cholangitis). Group A presented higher CA 19-9 values as compared to group B. Significant correlations were found in group B but not in group A between CA 19-9 and ALT, ALP and total bilirubin. Multiple regression analysis (CA 19-9 dependent and ALT, ALP and total bilirubin predictor variables) was significant only in group B. The standardized partial regression coefficients found to be significant were those of ALP and total bilirubin. We can conclude that CA 19-9 is an index of pancreatic cancer with satisfactory sensitivity and specificity. The presence of anatomical liver damage seems to increase the value of this index, probably releasing CA 19-9 into the bloodstream. Extra-hepatic cholestasis may also be an important factor in elevating CA 19-9 probably by reducing the hepatic catabolism of this glycoprotein.