Objective To evaluate the feasibility, safety and efficacy of percutaneous stent implantation for treating left main coronary artery (LMCA) stenosis. Methods Consecutive patients with unprotected left main coronary artery disease treated by stent-based percutaneous intervention (PCI) at 6 medical centers in China were enrolled. Procedural data and clinical outcomes were obtained from all patients. Results From January 2001 to December 2004, 138 patients (79 males and 59 females; mean age: 69.7±5.8 years) underwent PCI for LMCA stenosis. Bare metal stents (BMS) were implanted in 51 patients with non-bifurcational lesions and in 5 patients with bifurcational lesions from January of 2001 to June of 2003 (BMS group);. drug eluting stents (DES) were used unselectively to cover both bifurcational and non-bifurcational lesions in 86 patients from July of 2003 to December of 2004 (DES group). Procedural success rate of the 138 cases was 98% (135/138). One patient (0.7%) with bifurcation lesion who was treated with DES died from severe heart failure 2 weeks after the procedure. During a mean follow up period of 21.3±5.6 months, one patient died from renal failure, one from sudden cardiac death, 4 underwent target lesion revascularization (TLR) in the BMS group, which all occurred in patients with bifurcational lesions; whereas in the DES group no deaths occurred and only one patient with bifurcational lesion had TLR. Conclusions (1) PCI is feasible and relatively safe to treat unprotected left main coronary artery disease in elderly patients at medical centers with experienced professionals. (2) BMS and DES have similar immediate and long-term efficacy in the treatment of ostium and shaft lesions of the LMCA. (3) DES are strongly suggested in the therapy of distal bifurcation lesion of unprotected LMCA. Objective To evaluate the feasibility, safety and efficacy of percutaneous stent implantation for treating left main coronary artery (LMCA) stenosis. Methods Consecutive patients with unprotected left main coronary artery disease treated by stent-based percutaneous intervention (PCI) at 6 medical centers in China Procedural data and clinical outcomes were obtained from all patients. Results From January 2001 to December 2004, 138 patients (79 males and 59 females; mean age: 69.7 ± 5.8 years) underwent PCI for LMCA stenosis. Bare metal stents (BMS ) were implanted in 51 patients with non-bifurcational lesions and in 5 patients with bifurcational lesions from January of 2001 to June of 2003 (BMS group) ;. drug eluting stents (DES) were used unselectively to cover both bifurcational and non-bifurcational lesions in 86 patients from July of 2003 to December of 2004 (DES group). Procedural success rate of the 138 cases was 98% (135/138). One patient (0.7%) with bifurcation lesio n who was treated with DES died from severe heart failure 2 weeks after the procedure. During a mean follow up period of 21.3 ± 5.6 months, one patient died from renal failure, one from sudden cardiac death, 4 underwent target lesion revascularization (TLR) in the BMS group, which all occurred in patients with bifurcational lesions; while in the DES group no deaths occurred and only one patient with bifurcational lesion had TLR. Conclusions (1) PCI is feasible and relatively safe to treat unprotected left main coronary artery disease in elderly patients at medical centers with experienced professionals. (2) BMS and DES have similar immediate and long-term efficacy in the treatment of ostium and shaft lesions of the LMCA. (3) DES are strongly suggested in the therapy of distal bifurcation lesion of unprotected LMCA.