Aim To investigate the effects of tranilast on proliferation and c-myc protooncogene expression in vascular smooth muscle cells(VSMC)Methods In vitro cultured rat VSMCs model was established.3H-thymidine (3H-TdR)incorporation test and, reverse transcription-polymerase chain reaction (RT-PCR) technique were used.Results Both platelet derived growth factor-AB(PDGF-AB)and AngiotensinⅡ(AtⅡ) Were able to induce expression of c-myc protooncogene and in-creased DNA synthesis in VSMCs.Tranilast markedly inhibited the DNA synthesis in VSMCs in-duced by both PDGF-AB and AtⅡ. In the mean while,the drug was able to inhibit the c-myc protoonco-gene expression in VSMCs induced by both PDGF-AB and AtⅡas well.Conclusion Tranilast can inhibit VSMCs prolifera-tion and expression of c-myc protooncogene. The in-hibitoty effect of tranilast on the proliferation of VSM-Cs may be related to the inhibition of c-myc expres-sion.