AIM: To study the effect of oydin G2 on proliferation of gastric adenocarcinoma cell line-SGC-7901 cellin vitro.METHODS: By use of cation lipofectamine transfection reagent,the pIRES-G2 and pIRESneo plasmids were transferred into SGC-7901cell line. Anticlones were selected by G418. Positive clones were observed and counted using Giemsa staining.Cell proliferative ability was assayed by MTT.RESULTS: (1) The done number of pIRES-G2 group decreased,clone volume reduced. The number of cell dones in pIRESneo group was 87±3, that of pIRES-G2 group was 53±4,occupying 60.1% of pIRESneo group, there was significant difference obviously (P＜0.01, t=-15.45). (2) The average absorbance of clone cell obtained by stable transfection of pIRES-G2 at 570 nm was 1.6966±0.2125, the average absorbance of clone cell obtained by stable transfection of pIRESneo at 570 nm was 2.1182±0.3675, there was significant difference between them (P＜0.01, t=3.412).CONCLUSION: Cydin G2 can inhibit SGC-7901cell proliferative ability obviously, it may be a negative regulator in cell cycle regulation.