Aim To study the inhibitory effect of locally delivered c-sis proto-oncogene antisense oligodeoxynucleotide (ODN) on aortic smooth muscle cells (ASMC)proliferation and neointimal thickening. following balloon angioplasty in the rabbit aorta at differential time.Methods 60 male New Zealand, White Fabbits were treated with local delivery of c-sis antisense ODN,c-sis sense ODN, or 0. 9% salt solution via balloon catheter following aorta balloon injury, ASMC proliferation and area in neointima was assessed with immunohistochemistry and image analyzer at 3, 7, 14, 28 days after local delivery.Results ASMC proliferation in neointima were reduced 69. 8%. 59 %, 51. 9%, 47. 8% in c-sis antisense ODN-treated group compared to c-sis sense ODNtreated group at 3, 7, 14, 28 d following aortic injury respectively; and the inhibitory rate of neointimal hyperplasia was 48. 9%, 77. 8%, 72. 6%, 70. 8% at the same time respectively.Conclusion The locally deliveried C-sis antisense ODN inhibited ASMC proliferation and neointimal thickening following rabbit aortic injury, the inhibitory effect was the highest at 3 d and 7 d, then reduced slowly. and caused by antisense mechanism.