Abstract: Objective To study the inhibitive effect of isorhamnetin on epidermal growth factor receptor(EGFR)signal pathway of human gastric carcinoma cells in vit ro.Methods The inhibitory rate was calculated after the human gastric carcinoma SGC-7901 cells were treated with 018×10^-4,112×10^-4,214×10^-4mol/L isorhamnetin,10% RPM I,0.048mol/L fluorouracil.Expression of EGFR,grb2 and activity of AP-1 were measured by R T-PCR and calcium phosphate-DNA coprecipitation transfection after the SGC-7901 cells were transfected with EGFR and grb2 antisense by Lipofect.Results Inhibitive rate of 55.06%,62.03%,66.46%,70.25% occurred,respectively after 24h of 0.8×10^-4,1.2×10^-4,2.4×10^-4 mol/L isorhamnetin and 0.048mol/L fluorouracil treatment.Expression of EGFR,grb2 mRNA and AP-1 activity were significantly decreased in a dose-dependent manner after 24h of 0.8×10^-4,1.2×10^-4,2.4×10^-4 mol/L isorhamnetin treatment.The blockage of EGFR significantly increased the expression of grb2 and AP-1 activity.The transfection of grbantisense significantly enhanced AP-1 activity,but the expression of EGFR mRNA wasn't significantly affected.Conclusion Isorhamnetin can significantly inhibit proliferation of human gastric carcinoma SGC-7901 cells by controlling the EGFR signal pathway.