This investigation was undertaken in order to analyse the expression of tumor associated antigen CA 242 in normal pancreas, in chronic pancreatitis and in pancreatic ductal adenocarcinoma, and to find out if the expression of CA 242 in carcinoma specimens would have prognostic significance. The expression of CA 242 was examined in the tissue specimens by the avidin-biotin-immunoperoxidase technique. According to our results, normal pancreas showed no or only weak staining for CA 242, whereas chronic pancreatitis samples stained somewhat intensely. Five out of 39 adenocarcinomas were negative for CA 242, 5 showed weak staining and 29 showed intermediate or intense staining. Positive staining was found mostly in the ductal cells as well as in intraluminal contents. We found no statistically significant difference of CA 242 expression between different grades. The staining intensity and survival had no clear statistical correlation but all carcinoma patients whose survival time was more than twelve months showed an intense staining for CA 242. The results suggests that the expression of tumour associated antigen CA 242 may have prognostic significance in pancreatic adenocarcinoma.