Abstract: Objective 　To explore the proteomic differences among the high and low differentiation colorectal carcinoma tissues by using two-dimensional gel elect rophoresis (2-DE) and mass spectromet ry. Methods 　In sample preparation, the fresh carcinoma tissue was cut off from the specimen and these tissues were classified into three groups according to the postoperative pathological diagnosis : high differentiation carcinoma, low differentiation carcinoma and normal epithelium. Protein separation was performed using 2-DE. After silver-staining, the images of the gels were scanned and analyzed to find the differentially expressed protein-spots in each group. We acquired the peptide mass fingerprintings ( PMF) of differentially expressed protein-spots by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and identified the proteins by data searching in the Mascot-database. Protein expression was assayed by immunohistochenistry. Results 　We detected calreticulin precursor and O98007-like protein expressed exclusively and AA H10915 和AAH75839 increased in both the two cancer groups. In high differentiation group, E980237 and tubulin beta chain expressed exclusively and triosephosphate isomerase and fatty acid-binding protein increased. In low differentiation group, 2 HHEB and Zinc finger protein312-like protein expressed exclusively and Q9 TQL5-like protein increased (over than 5 fold) . The HSP27 positive rate is significantly higher in high differentiation group than low differentiation group . Conclusion 　Some differentially expressed proteins existed in high and low differentiation colorectal carcinoma as well as the normal colon mucosa. These proteins are related with colorectal carcinoma cell differentiation.