The immunoreactivity of two monoclonal antibodies, CO17-1A (recognizing 17-1A antigen) and B72.3 (recognizing TAG-72), was examined in pancreatic tissues from individuals without pancreatic disease and from those with benign and malignant pancreatic disease. 17-1A antigen was found in all cells in the normal tissue, whereas TAG-72 was present in the duct cells in only one case. Both antigens were present in benign diseases; however, in some cells and in some conditions, TAG-72 was significantly less common (P less than .01 to .001) than 17-1A antigen. In pancreatic cancer, 17-1A antigen was present in 87% of cases and TAG-72 antigen was present in 92% of cases. The results indicate that B72.3 is more specific to pancreatic cancer than C017-1A.