Objective To evaluate the effect of antisense angiotensin Ⅱ type Ⅰ (AT 1R) oligodeoxynucleotide (ODN) on intimal hyperplasia in rat carotid artery after nitrogen drying injury.Methods Sixty rats were randomized into six groups:antisense(A) group,sense(S) group,mismatch(M)group,cationic lipid DOTAP(D) group,control(C) group and false(F) group.Different ODN was applied locally through double balloon pressure drive system and DOTAP delivery system,group C received only nitrogen drying endothelial.group D delivery DOTAP alone,group F used 0.9 percent NaCl irrigation left common carotid.The rats were fed with routine diet.After two weeks,the animals were killed and defined segmient of artery was sectioned and the histological sections were stained with HE staining.The cross-section of artery was examined microscopically and the image was digitalized by color image analysis system.The lumen area,the ratios of intima/media area,intima thickness,the ratios of intima/media thickness and the covery ratios of intima were calculated and analyzed statistically among the groups.Result The lumen area of group A was larger than that of group S,group M,group D and group C(P<0.05);The intima area,the ratios of intima/media area,intima thickness,the ratios of intima/media thickness and the covery ratios of intima of group A were less than that of group S,group M, group D and group C(P<0.01).Conclusion The AT 1R plays an important role in the mechanism of intima hyperplasia.Antisense ODN of AT 1R significantly inhibited the intimal hyperplasia in injury rat carotid artery in sequence-specific manner.The investigation provides a new genetic therapeutic strategy for the prevention of restenosis after angioplasty.