In order to determine the diagnostic usefulness of the dosage of carbohydrate antigen (CA 19-9) serum levels in pancreatic diseases, 38 patients with pancreatic lesions proved at laparotomy were studied. Pancreatic lesions were classified into two groups: a) group I: pancreatic adenocarcinoma (17 cases) b) group II: benign pancreatic diseases (21 cases). CA 19-9 serum levels were statistically higher in patients of the first group (p less than 0.001). All patients except one with CA 19-9 higher than 60 U/ml had pancreatic carcinoma. All patients except two with CA 19-9 less than 60 U/ml had a benign lesion. The sensitivity and specificity of CA 19-9 were 88 and 95 p. 100 respectively. These results show that CA 19-9 dosage is useful in distinguishing between benign and malign lesions of the pancreas.