ObjectiveTo find early diagnostic biomarkers for colorectal carcinoma by comparing differential expressingproteins from colorectal carcinoma and normal colorectal tissues. MethodsColorectal carcinoma tissues and paired normal tumoradjacent colorectal tissues were collected, and tissue total protein was extracted; differential proteome profiles were established and analysed by means of immobilized pH gradientbasedtwodimesional polyacrylamide gel electrophoresis(2DPAGE) and matrixassisted laser desorption/ionization time of flight mass spectrometry(MALDITOFMS). ResultsWellresolved, reproducible2DE profiles of human colorectal carcinoma tissues and paired normal tumor adjacent colorectal tissues were obtained. For tumor tissue, a total of 1098±28 spots were detected, and for normal tissue, 760±45 spots were detected. For normal tissue, The average deviation of spot position was（0.542±0.12）mm in IEF direction and（0.933±0.098）mm in SDSPGE direction for tumor tissue. The average deviation of spot position was（ 0.745±0.130）mm in IEF direction and（1.233±0.272）mm in SDSPGEdirection. 30 differential expressing proteins were analysed by mass spectrometry and bioinformation,
16 of them were well characterized including Apolipoprotein A1 (apoA1),calreticulin precursor,glutathione Stransferase, hepatic fatty acidbinding protein、heat shock protein 27 ect. ConclusionsDifferential expression proteins can be candidate biomarkers for early diagnosis of colorectal carcinoma; and proteomic technique is valuable for screening the diagnostic biomarkers.