Stents are constructed with predefined radial strength which, on occasion, may be insufficient to support a resistant lesion.We prospectively assessed the need for, and safety of, implanting a second stent within the first, during the index procedure, in a consecutive series of 500 patients undergoing percutaneous coronary intervention (PCI) by a single operator in the period 1998 2001. The indication was a lesion that appeared angiographically suboptimal after full balloon/stent expansion to high pressure with appropriate sizing. Visible thrombus was an exclusion. Stents were slotted tubes or ring designs whenever possible. Clinical follow-up was > 1 year and angiographic re-study was performed when indicated.We identified 18 patients/lesions (3.6%) that required implantation of a stent within a stent. The appearance was due to tissue/stent prolapse in 72%, edge dissection in 17%, narrow stent inflow/outflow in 5.5% and inadvertent stent detachment in 5.5%. There were no lesion-related acute or in-hospital complications. There was no late thrombosis or death. Follow-up was 21 10 months, and revealed 11% target lesion revascularization, of which half were at the site of stent overlap.Stenting the stent, where extra support is required, is safe and effective.