Objective: To evaluate the safety and clinical efficiency of percutaneous coronary intervention (PCI) in elderly patients with coronary heart disease and type 2 diabetes mellitus. Methods: 65 elderly patients with coronary heart disease and type 2 diabetes mellitus who underwent percutaneous coronary intervention were compared with 70 patients without diabetes mellitus in lesion characteristics of coronary artery, successful rates and major adverse cardiac events(MACE). Result:Triple vessel disease and complex lesions were higher in the diabetics group than those in the non-diabetics group (35.4% vs 18.6%; 69.2% vs 51.4%，P﹤0.05). The success rate of PCI and the rate of MACE during the hospitalization period were found no difference. The follow-up period for all the patients was in the range of 9 to 24 months. The rate of re-angina and target vessel revascularization were higher in the diabetics group than those in the non-diabetics group (14.1% vs 8.7%; 12.5% vs 2.90%, P﹤0.05). Cardiac deaths, nonfatal myocardial infarction, the incidence of restenosis were found no difference. Late acute stent thrombosis did not occur in both groups. Conclusion: In elderly patients with coronary heart disease and diabetes mellitus, PCI was a safe and effective procedure.