Abstract: ObjectiveTo assess the inhibitory effect and mechanism of soybean isoflavones(ISF)combined with vinorelbine(NVB)on proliferation of A549 lung carcinoma cells.Methods(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)assay was used to examine the effects of ISF and NVB on proliferation of A549 cells,and their combined effect was analyzed by Weeb's method.Transmission electron microscopic technique was used for the determination of morphology of A549 cell apoptosis.ResultsISF and NVB inhibited the proliferation of lung carcinoma cells in a time-and concentration-dependent manner.The inhibitory indexes of ISF at the concentration of 20-80 mg/L were 15%-23%,and the inhibitory indexes of NVB at the concentration of 8-32 mg/L were 53%-80% at 48 hours.The concentration-dependent pattern in the combination of ISF and NVB were also detected with 40 mg/L ISF.The synergistic or additive effect on inhibition of A549 cell proliferation was detected for NVB at the concentration from 8 to 32 mg/L with the inhibitory indexes of 71%-93%.ConclusionISF combined with NVB can enhance the growth inhibition of A549 lung carcinoma cells and play a synergistic antitumor effect.