Aim To observe the role of puerarin on the proliferation of vascular smooth muscle cells(VSMC) induced by thrombin and the effect of puerarin on the Bcl-2 protein and thrombin receptor(TR) mRNA expression. Methods Cell number and cell cycle analysis using flow cytometry were adopted as two different indicators of effects on proliferation of VSMC.Western blot was used to indicate the changes of Bcl-2 protein,and reverse transcription-polymerase chain reaction(RT-PCR) was used to evaluate TR mRNA expression,with treatment of thrombin and puerarin after 24 h. Results Thrombin can significantly increase the cell numbers of VSMC,the peak of proliferation curve is at 24 h,and the effect of T is in a dose dependent manner(0.1～1.0 u/L).1.5×10~(-5)～1.5×10~(-3) mol/L puerarin can significantly suppress this stimulation of VSMC proliferation and DNA synthesis.Western blot demonstrated that treated with thrombin and puerarin after 24 h,thrombin can significantly increase Bcl-2 protein.1.5×10~(-5)～1.5×10~(-3) mol/L puerarin can significantly suppress this increase.RT-PCR demonstrated that thrombin can increase TR mRNA expression significantly,and 1.5×10~(-3) mol/L puerarin can suppress this increase. Conclusions Puerarin can suppress the proliferation and DNA synthesis of VSMC promoted by thrombin.This inhibitory effects of puerarin are closely related with the suppression of Bcl-2 protein,and partly related with the suppression on TR mRNA.