Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a membrane protein that can support the binding, internalization, and proteolytic degradation of oxidized low-density lipoprotein. The LOX-1 expression increases in the neointima after balloon injury. To develop an efficient compound to inhibit LOX-1, we designed and synthesized a novel gene silencer pyrrole-imidazole (PI) polyamide targeting the rat LOX-1 gene promoter (PI polyamide to LOX-1) to the activator protein-1 binding site. We examined the effects of PI polyamide to LOX-1 on the LOX-1 promoter activity, the expression of LOX-1 mRNA and protein, and neointimal hyperplasia of the rat carotid artery after balloon injury. PI polyamide to LOX-1 significantly inhibited the rat LOX-1 promoter activity and decreased the expression of LOX-1 mRNA and protein. After balloon injury of the arteries, PI polyamide to LOX-1 was incubated for 10 minutes. Fluorescein isothiocyanate-labeled PI polyamide was distributed to almost all of the nuclei in the injured artery. PI polyamide to LOX-1 (100 microg) significantly inhibited the neointimal thickening by 58%. PI polyamide preserved the re-endothelialization in the injured artery. PI polyamide significantly inhibited the expression of LOX-1, monocyte chemoattractant protein-1, intercellular adhesion molecule-1, and matrix metalloproteinase-9 mRNAs in the injured artery. The synthetic PI polyamide to LOX-1 decreased the expression of LOX-1 and inhibited neointimal hyperplasia after arterial injury. This novel gene silencer PI polyamide to LOX-1 is, therefore, considered to be a feasible agent for the treatment of in-stent restenosis.