Objective：To establish a twodimensional electrophoresis (2DE) gel map of 2 earlystage lung adenocarcinoma tissues with and without RASSF1A expression, so as to screen and identify differential proteins. Methods: Five earlystage lung adenocarcinoma tissues with RASSF1A expression and 5 without RASSF1A expression were screened out by Western blotting assay. The total soluble proteins of the tissue were extracted and were separated by immobilized pH gradient based twodimensional gel electrophoresis to set up the 2DE gel map of the 2 adenocarcinoma tissues. The differentiallyexpressed proteins were analyzed by PDQuest image analysis software and identified by matrixassisted laser desorption/ionization time of flight mass spectrometry (MALDITOFMS); the protein database was searched to further characterized the differential proteins. Results: A wellreproducible 2DE gel map of the 2 adenocarcinoma tissues with and without RASSF1A expression was established and 17 differential protein spots were screened out. Nine of 17 differential protein spots were selected for MALDITOFMS study and satisfactory peptide mass fingerprints were obtained for all the 9 spots. Searching of the protein database revealed 5 candidate proteins and they were: cytochrome b5, 60S acidic ribosomal protein P2, carbonic anhydrase 1, pyrroline5carboxylate reductase 1, and apolipoprotein AⅠ precursor.Conclusion: We have successfully obtained the 2DE gel images of 2 earlystage lung adenocarcinoma tissues with and without RASSF1A expression, and from which we have identified 5 differential proteins,which paves a way for studying the signal transduction pathways involving RASSF1A.