Abstract： Background Patients aged over 85 years have been under-represented in percutaneous coronary intervention (PCI)trials despite an increase in referrals for PCI. The long-term safety and efficacy of percutaneous coronary stenting in patients aged over 85 years with acute coronary syndrome (ACS) remain unclear. Moreover it is unknown whether there are differences between bare metal stent (BMS) and drug eluting stent (DES) in this special population.Methods A total of 80 patients with ACS aged over 85 years undergoing stenting (BMS group n=21 vs DES group n=59)were retrospectively studied. In-hospital, one year and overall clinical follow-up (12-36 months) of major adverse cardiac events (MACEs) including cardiac deaths, myocardial infarction, target lesion revascularization (TLR) and target vessel revascularization (TVR) as well as stroke and other major bleeding were compared between the two groups.Results In the entire cohort, the procedure success rate was 93.8% with TIMI-3 coronary flow post-PCI in 93.8% of the vessels and the procedure related complication was 17.5%. The incidence of in-hospital MACEs in BMS group was higher (14.3% vs 6.8%, P=0.30). The 1-year incidence of MACEs in DES group was 7.0% while there was no MACE in the BMS group. Clinical follow-up for 12-36 months showed that the overall survival free from MACE was 82.9% and the incidence of MACE in the BMS group was lower (5.3% vs 21.1%, P=0.20). Multivariate regression analysis showed that the creatinine level (OR:1.013; 95%C1: 1.006-1.020; P=0.004) and hypertension (OR:3.201; 95%C1: 1.000-10.663;P=0.04) are two major factors affecting the long-term MACE.Conclusions Percutaneous coronary stenting in patients aged over 85 years is safe and provides good short and long-term efficacy. Patients with renal dysfunction and hypertension may have a relatively high incidence of MACE.