In this study, pancreatic tissue carcinoma antigen (PCA) was extracted from human pancreatic adenocarcinoma tissue, partially purified by chromatography, and confirmed by immunological methods. It was demonstrated by immunofluore-scence technique thatPCA resided in the cytoplasm and plasma membrane of pancreatic carcinoma cells. The specific antisera against PCA was acquired from immunized rabbits. The antiPCA antibody had specificity to sera with pancreatic carcinoma cells. We established ELISA for determination of PCA, and detected 233 cases of pancreatic carcinoma, alimentary cancer and alimentary benign disease with ELISA. It is indicated that PCA is clearly different from other tumor markers such as PCA, CEA and POA, and is a new tumor marker specific to pancreatic carcinoma.