Background and objective: Slp2 gene is one of the differential expression genes in lung cancer tissues and normal controls, the aim of this study is to observe the effects of antisense Slp2 gene on growth and proliferation in lung cancer cell lines. Methods: Total RNAs were extracted from 4 lung cancer cell lines (A549, GLC-82, NCI-H446, NCI-H460), Slp2 gene expressions were detected at mRNA level by reverse transcription-polymerase chain reaction (RT-PCR); antisense Slp2 gene plasmid was constructed and transfected into GLC-82, NCI-H446 and NCI-H460 cells with lipofectinmin. The expressions of Slp2 gene were analyzed by RT-PCR in these cells before and after transfection; Flow cytometry, MTT assay and soft agar culture were used to investigate the effects of antisense Slp2 gene transfection on DNA content changes in cell cycle, proliferation and colony formation ability of these cells. Results: Slp2 gene was positive expressed in A549, GLC-82, NCI-H446 and NCI-H460 cell lines. The proliferation of GLC-82, NCI-H446 and NCI-H460 cells were inhibited by antisense Slp2 gene conspicuously. The flow cytometry experiments showed accumulation of transfected cells in G2-phase, for one time concomitant appearance of apoptotic cells of sub-G1 (hypodiploid) DNA content was observed in transfected NCI-H446 cell. Dramatic inhibition of colony formation in soft agar was observed in those transfected lung cancer cell lines. Conclusion: The results suggest that Slp2 gene might be a key gene in lung cancer cell growth and proliferation.