Abstract: Objective To identify novel tumor associated antigens(TAA)in esophageal squamous cell carcinoma(ESCC).Methods The proteins extracted from tissues of ESCC were separated by two dimensional polyacrylamide gel electrophoresis,and followed by Western blot analysis in which sera from 20 patients with ESCC and 20 healthy controls were tested for primary antibodies.Positive spots were excised from Coomassie blue-stained gels and the tryptic peptides were analyzed by matrix-assisted laser disorption/ionization time-of-flight mass spectrometry(MALDI-TOF-MS).The expression of the candidate TAA in ESCC tissue was detected by immunohistochemical staining(IHC).Results Sera from patients with ESCC yielded multiple spots,one of which was identified as heat shock 70kDa protein 8(HSC70 or HSPA8)by MALDI-TOF-MS.The immunohistochemistry analysis showed that HSC70 was located in both cytoplasm and nucleus,and had a higher expression in cancer tissues than paracarcinoma normal tissue.Conclusion The combination of immunoblot and mass spectrometry may identify some novel TAAs.These results suggested that HSC70 may play a role in tumorigenesis of ESCC,and may be a key diagnostic and therapeutic target.