Background and Objectives : Insulin resistance is important risk factor for coronary artery disease. However, There is no data regarding their effect on the outcomes of percutaneous coronary intervention (PCI) in non-diabetic patients. Subjects and Methods : We studied 101 consecutive patients (59.4짹11.32 years, male : female = 66 : 35) who underwent elective coronary angiography. The clinical diagnoses on admission were stable angina (33.7%), unstable angina (43.6%), acute myocardial infarction (11.9%). Insulin resistance was evaluated by the homeostasis model assessment of insulin resistance (HOMA-IR). The patients were divided into two groups: Group I (n=66, 57.9짹11.26 years, male 63.6%) who had HOMR-IR <2.6 and Group II (n=35, 62.4짹10.99 years, male 68.6%) who had HOMA-IR ���2.6. In-hospital and 30-day major adverse cardiac events (MACE) were compared between two groups. Results : The levels of fasting plasma glucose, fasting insulin, hemoglobin A1c were significantly higher in Group II than in Group I. Significant correlations were observed between HOMA-IR and body mass index (r=0.466, p<0.001), triglyceride (r=0.195, p=0.039) and high density lipoprotein-cholesterol (r=-0.212, p=0.036). PCI was perfromed in 55 patients (54.5%). No significant differences in 30-day MACE were observed between two groups. However, in a subgroup of the patients underwent PCI, in-hospital MACE was higher in Group II than in Group I (2.9% vs. 25.7%, p=0.017). Multivariate analysis revealed that preprocedural TIMI flow <3 (OR 0.31, 95% CI 0.00 to 0.54, p=0.027) and HOMA-IR ���2.6 (OR 62.29, 95% CI 3.13 to 187.01, p=0.016) were independent predictors of angiographic success. Conclusion : Non-diabetic patients with HOMA-IR ���2.6 had significantly higher in-hospital MACE. Increased HOMA-IR level may have prognostic significance in non-diabetic patients who undergo PCI.