Background and Objectives:Despite the dramatic reduction in restenosis conferred by drug-eluting stents(DES), restenosis remains a significant problem for real-world patients. Restenosis is a complex phenomenon,and a variety of stent-, drug-, patient- and lesion-related factors have been studied as the determinants of restenosisafter DES implantation. Methods and Results:The stent delivery system, the polymer and the drug are integralcomponents of DES, and these are the device-specific factors that can affect restenosis. While the sirolimuselutingCypher stent appears to provide better outcomes than the paclitaxel-eluting Taxus stent in high-risk patientgroups with complex lesions, such differences between the two DES are not apparent in the low-risk groups.Diabetic patients are generally prone to restenosis after percutaneous coronary intervention, but there areconflicting findings regarding the impact of diabetes mellitus on restenosis after DES implantation. The postinterventionfinal lumen area continues to be the most important determinant of restenosis after DES implantation,indicating that a greater stented area contributes to a decreased rate of restenosis even in the DES era. Nonuniformstrut distribution and stent fracture also contribute to the development of restenosis after DES implantation.In addition, the risk of restenosis increases linearly according to lesion length, and a “full metaljacket” approach in small vessels is related to a high risk of DES failure. Conclusion:Small vessel disease, diffusedisease and the type of DES are important predictors of restenosis after DES implantation. However, predictingrestenosis remains difficult, and this indicates the need for further studies in order to ultimately identify thosepatients who are at high risk for DES failure. (Korean Circulation J 2007;37:97-102)