Aim To investigate the effect of infection with adenoviral vector containing cDNA for human catalase on apoptosis of cultured human vascular smooth muscle cells (VSMC). Methods Human VSMC were infected with catalase -contained recombinant adenovirus (AdCat) in vitro. Catalase protein was detected by Western blot analysis. The VSMC apoptosis was determined by flow cytometry and TUNEL assay. Results The expression of catalase in VSMC infected with AdCat was significantly higher than that in uninfected VSMC. The number of TUNEL- labeled nuclei in AdCat-infected cells was greater than that in AdLacZ-infected or noninfected cells. The percentage of apoptosis cells in VSMC infected with AdCat was higher than that in control group (p<0.001). Conclusion These findings indicate that overexpression of Catalase promoted apoptosis in VSMC. It could be a new target to prevent the restenosis after percutaneous trans luminal coronary angioplasty .