To explore the the effect of RSV M 2-1 gene expression on the growth of human lung adenocarcinoma PAa cell line, the recombinant RSV M 2-1 gene eukaryotic plasmid PXJ 41/ M 2-1 was transfected to the human lung adenocarcinoma PAa cell line. Expression of the M 2-1 gene was examined by RT PCR and Western blot. The growth of the human lung adenocarcinoma PAa cell was observed by MTT curve, flow cytometry, the capacity of inherence, colony forming units and inoculation of nude mouse. The results showed that ①The desired fragments of M 2-1 gene were digested by restriction enzyme and RT PCR, respectively. ②The bands of M 2-1 gene protein were found by Western blot. ③ The ratio of transfected PAa cells in S phase of cell cycle was decreased, but increased in G 2 /M phase. Colony forming efficiency and units of the transfected PAa cell were increased, but the capacity of its inherence was decreased. ④Tumorogensising time of the transfected PAa cell in nude mouse was delayed, but its growing speed was increased. The tumor tissue transformed to some extent from adenocarcinoma to squamous carcinoma was found in the nude mouse. It is suggested that the M 2-1 gene may promote the growth of PAa cells, which may implicate some relationship between RSV and lung cancer.