Background Patients with end-stage renal disease have a high mortality from coronary artery disease, but the impact of moderate renal insufficiency on clinical outcomes after percutaneous coronary intervention (PCI) and the effect of drug-eluting stent implantation in these patients remain unclear. This study determined the long-term effect of moderate renal insufficiency on death and major adverse cardiac events (MACE) after stent based PCI and examined whether drug-eluting stent implantation could favourably influence clinical outcome.Methods Major adverse cardiac events and causes of mortality were determined for 1012 patients undergoing percutaneous intervention from January 1, 2002 to December 31, 2004 at Shanghai Ruijin Hospital. Based on estimated creatinine clearance levels, long term outcomes were compared between patients with estimated creatinine clearance ＜60 ml/min (renal insufficiency group; n=410) and those with estimated creatinine clearance ≥60 ml/min (control group; n=602). Subgroup analysis was also made for patients with renal insufficiency between drug eluting stent (n=264) and bare metal stent implantation (n=146) during PCI.Results During follow-up (average 17 months) after successful PCI, all causes of death (7.1% vs 2.3%, P＜0.01)and cardiac death (3.4% vs 1.0%, all P＜0.01) were significantly higher in renal insufficiency group than in control group. For patients with moderate renal insufficiency, drug-eluting stent implantation reduced significantly all causes of death (5.3% vs 10.9%, P＜0.05) and occurrence of major cardiac adverse events (15.1%vs 24.6%, P＜0.05) compared with bare metal stents.Conclusions Moderate renal insufficiency is an important clinical factor influencing the mortality after PCI in patients with coronary artery disease and the use of drug-eluting stents should be the preferred therapy for the improvement of long-term outcomes in such patients.