Abstract: Objective To investigate differential protein expression profiles of human colorectal carcinoma cell lines with different metastatic potentials and screen metastasis-associated proteins for analyzing the relationship between metastasis- associated proteins and the tumorigenesis, progression and metastasis of colorectal carcinomas. Methods With two-dimensional electrophoresis (2-DE) and matrix assisted laser desorption/ionization-time of flight-mass spectrometry, we analyzed the differentially expressed proteins in two human colorectal carcinoma cell lines SW620 and SW480 with high and low metastatic potentials, and screened for proteins associated with colorectal carcinoma metastasis. Results Image analysis software MalenieⅢ demonstrated good match and reproducibility of the 2-DE maps obtained from 3 independent experiments, with 1316±62 spots detected for SW620 cells and 1332±74 spots for SW480 cells with the average matching rate of 82% and 80%, respectively. The spots distributed in the greatest density at the isoelectric points of 4-7 and relative molecular mass weight of 20 000-70 000. Twenty-five distinctly different protein spots (14 spots for SW620 and 11 for SW480) in-gel digested by TPCK trypsin and 23 peptide mass fingerprint maps were obtained by mass spectrometry. Three highly matched proteins and 14 preliminarily matched proteins or fragments were obtained by analysis with Mascot software in the NCBInr database. Some of these differentially expressed proteins were related to gene transcription, cell cycle, signal transduction, cell apoptosis, etc, with possible involvement of cell differentiation, proliferation, invasion, adhesion, and metastasis of colorectal carcinoma. Conclusion The 2-DE protein expression profile of SW620 cells with high metastatic potential displays obvious difference from that of SW480 cells with low metastatic potential, and a variety of proteins can be involved in the metastasis of colorectal carcinoma.