Aim To better understand the inhibition of growthand induction of apoptosis in smooth muscle cells(VSMC) by nitric oxide (NO) and the mechanism inthese processes.Methods Cultured rat VSMC at passage 5 to 8 wereused for experiment. After reaching 60 % ～70 % con-fluence, VSMCs were preincubated for 24 h (at least)with serum free Dubecco's modified Eagle's medium(DMEM ) to become quiescent before the experiments.Then SNAP (0. 4 mol/L) was added to the medium.The cells were fixed with 3% paraformaldehyde after 8h. Expression of Bcl-2, Bax, P53, and Fas in VSMCwere examined by fluorescein immunocytochemistrymethods through ACAS 570.Results Expression of Bcl-2 was decreased by NO.But expression of Bax , P53 , and Fas were increased byNO.Conclusion Bcl-2, Bax, P53, and Fas may take partin the effects of NO on inhibition of growth and induc-tion of apoptosis in VSMCs.