Aim To determine if an association exists between restenosis after percutaneous coronary intervention and heme oxygenase-1 (HO-1). A dinucleotide (guanosine thymidine, GT) repeat in the promotor region of the HO-1 gene shows a polymorphism that modulates the level of gene transcription. Methods This retrospective study included 118 patients of the Han nationality (92 men; mean age 62.3 years, standard deviation 9.8) who underwent successful stent implantation. Patency follow-up was evaluated using angiography. The length of GT repeat was confirmed using polymerase chain reaction (PCR) amplification and electrophoresis. Selected samples were sequenced by means of Sanger's method. The association of patency and the length of GT repeat in the HO-1 gene promotor was assessed in univariate and multivariate analyses. Results In-stent restenosis was found in 68 (58%)out of 118 patients. Patients with short (<25GT) dinucleotide repeats in the HO-1 gene promotor on either allele had restenosis significantly less often than patients without short dinucleatide repeat (47.5% vs 68.4%,p< 0.05 ). Multivariate analysis revealed a significantly similar result after controlling certain possible confounding factors (odd ratio 0.406, 95%CI 0.185 ～0.891, p<0.05). Conclusions In this patient population, short GT repeat alleles of the HO-1 gene promotor polymorphism were associated with reduced post-PCI restenosis.