Objectives To examine whether obesity has a similar effect on long-term prognosis between men and women undergoing a percutaneous coronary intervention (PCI). Methods We separately examined 3926 men and 2157 women undergoing PCI with drug-eluting stents between January 2004 and December 2006. All the patients were categorized according to BMI: normal weight (< 25 kg/m(2)), overweight (25-29.9 kg/m(2)), and obese (>= 30 kg/m(2)). The primary endpoint was major adverse cardiovascular events (MACE), defined as a composite of cardiac death and nonfatal myocardial infarction. The median follow-up was 26 months. Results The MACE rate was significantly higher in obese than in normal-weight and overweight patients among men (6.8 vs. 3.5 vs. 4.2%; P = 0.001) but not among women (5.1 vs. 4.4 vs. 4.1%; P = 0.684). Further categorization of BMI showed a linear association between the risk of MACE and BMI in men, with a graded increase in obesity grade I (30-34.9 kg/m(2)) and grade II/III (Z35 kg/m(2)) groups compared with normal-weight individuals [hazard ratio (HR) 1.94; 95% confidence interval (CI) 1.22-3.06; P = 0.005 for obesity grade I and HR 2.62; 95% CI 1.50-4.56; P = 0.001 for obesity grade II/III]. In women, the risk of MACE showed no difference in obesity grade I group, whereas there was a significant increase in the obesity grade II/III group compared with normal-weight patients (HR 2.15; 95% CI 1.10-4.18; P=0.025). Conclusion In patients undergoing PCI, BMI is associated with a risk of MACE in both men and women. However, BMI exerts relatively less effect on women than on men. Coron Artery Dis 23:404-411 (C) 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.