Aim To observe the induction of apoptosis in vascular smooth muscle cell (SAC) by the introduction of wild-type P53 gene and investigate the mechanism of inhibition for SMC proliferation by wild-type P53 gene.Methods A replication--deficient adenovirus vector encoding a wild-type P53,AdCMV P53,was constructed and trans feeted into the cultured rabbit aortic SMC.The cell cycle of SMC was analysed with flow cytometry. The 3H-thymidine incorporation assay was used to measure DNA synthesis in SAC. The apoptotic cells was determined by termmed deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and agarose gel electrophoresis.Results Introduction of wild-type P53 gene into SMC can arrest 77% of AdCMV P53--infected cells at GO/GI phases of the cell cycle, leading to inhibition of DNA synthesis. Overexpression of wild-type P53 induced apoptosis of cells infected with AdCMV P53 as detected by TUNEL and flow cytometry. Electrophoresis of genomic DNA showed internucleosomal fragments of DNA isolated from the AdCMV P53--infected SMC.Conclusion Wild-type P53 gene suppress SMC pro liferation by induction of apoptosis in SMC.