Abstract： Objective To evaluate the effect of genistein on the secretion of SMemb and on extracellular matrix of rat mesangial cells cultured in high glucose.Methods Control group(low glucose of 100mg/dl without genistein)and experiment group(high glucose of 450mg/dl with 0,5,10,50,100,200μmol/L of genistein)were incubated for 12,24,48 hrs.The expressions of SMemb mRNA,MMP-2 mRNA and TIMP-1 mRNA and synthesis of Fn were examined.Results Genistein inhibited the expression of SMemb mRNA,decreased Fn secretion(P<0.01 or 0.05).Genistein also increased the semi-quantitative ratio of MMP-2/TIMP-1 mRNA in dose-dependent and time-dependent manner.Conclusions Under hyperglycemia,genistein can decrease the overexpression of SMemb mRNA,and relieve accumulation of extracellular matrix.