The expression of the blood group antigens Le a, Le b, Le x, Le y and the carbohydrate antigens CA 19-9 and CA-50 was studied in 20 ductal pancreatic carcinomas, 24 pancreases with chronic pancreatitis and 10 normal fetal and adult pancreases. CA 19-9, CA-50 and Le a showed the strongest staining intensity, the highest percentage of labelled cells, and a membrane-bound expression pattern in epithelial cells of normal pancreas, chronic pancreatitis and well differentiated (G1) carcinoma; in moderately and poorly differentiated carcinomas (G2/3) it was predominantly cytoplasmic. The staining pattern of Le b and Le x was less clearly membrane-bound but varied with cytoplasmic and Golgi-located distributions in all pancreatic specimens. Le y revealed a consistent granular antigen expression in the Golgi-region of ductal epithelial, acinar and carcinoma cells. None of the antibodies allowed a morphological differentiation by their expression pattern between hyperplastic, metaplastic and dysplastic or neoplastic cells. The differences in their staining patterns were quantitative and did not allow a qualitative differentiation between chronic pancreatitis and pancreatic carcinoma. We found coexpression of Le a and Le b antigens in 46/54 pancreatic specimens. All but 7 pancreata were CA 19-9 positive. An association between Le x, y and Le a, b antigen expression could not be noted in our material.