HLCDG1, which locates in chromosome 5q33, is a novel gene cloned recently. The HLCDG1 expression was significantly down regulated in the primary lung carcinoma. It was previously studied that HLCDG1 acted like a tumor suppressor gene. In this paper, proteomics studies were performed to analyze the proteomic expression patterns in the HLCDG1-transfected human lung carcinoma cell line (A549-HLCDG1) and in the control vector-transfecred human lung carcinoma cell line (A549-vector). Employing two dimensional gel eleetrophoresis (2DE), the global pattern of protein expressions in A549-HLCDG1 human lung adenocarcinoma cell line expressing stably HL-CDG1 gene were compared with those of control A549-vector cell line to generate a differential protein expression catalog. Forty-two differentially expressed proteins were screened. Thirteen differential proteins were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), which were 6 upregulated (MSH5, MOD, MDH precursor, ETFβ, Prxd Ⅵ and JM23) and 7 downregulated (PLC-δ1, hnRNPA2,hnRNPB1, TIM, TCTP, nm23H-1 and PrxdⅤ) proteins in A549-HLCDG1 cells compared to control A549-vector cells. The above identified proteins were involved in energy metabolism, transcription regulation, antioxidation,cell cycle, metastasis, DNA methylation and mismatch repair. Therefore, these differential expression proteins by HLCDG1 transfection may play some important roles for investigation of the biochemical basis of growth suppression of HLCDG1 gene in lung carcinoma cells A549. Further understanding of this data base may provide valuable resources for the developing novel diagnostic markers and therapeutic targets of lung cancer.