Background: Drug-eluting stents (DES) have shown their efficacy in reducing neointimal hyperplasia. However, changes occurring in native vessels surrounding stents have not been well studied. The aim of this study is to investigate coronary peristent remodeling after implantation of sirolimus-eluting stents (SES, Cypher, Cordis) versus zotarolimus-eluting stent (ZES, Endeavor Sprint, Medtronic) using intravascular ultrasound (IVUS). Methods : The study population comprised 100 patients (male n=63, age 62짹8 years) with acute myocardial infarction from the DES registry of Severance Cardiovascular Hospital who were treated either with SES (n=41) or ZES (n=59) between January 2006 and December 2008 and evaluated with serial intravascular ultrasound at 9 months. Patients with significant restenosis were excluded from the analysis. Changes in IVUS parameters from immediate post-PCI to follow-up were compared between SES and ZES. Results: Baseline clinical and lesion characteristics were not different between the two DES types. Neointimal volume obstruction was significantly greater in ZES compared with SES (19.2짹15.6 % vs 3.6짹6.7%; p<0.001). The external elastic membrane area was significantly more increased in patients treated with SES compared with ZES (2.6짹2.9��� vs 1.8짹2.1���; p=0.04) at 9-month follow-up. Positive persistent remodeling (>10% increase EEM area) was more frequently observed in SES group compared to ZES group (70.7% vs 59.3%; p=0.03).Conclusion : SES was more effective in inhibiting neointimal growth compared with ZES. However, SES also caused more positive persistent vascular remodeling. The positive peristent vascular remodeling may contribute to development of peristent aneurysm, however the clinical implication of our observation is not known.