Recently, the number of patients in whom a drug-eluting stent (DES) has recently been implanted and who need to undergo surgery or the most invasive procedure is increasing. However, there are limited data about the risk of perioperative thrombosis of DES. We evaluated the incidence and the risk factors of DES thrombosis during the perioperative period. Between January 2002 and December 2006, 141 patients who underwent surgery requiring discontinuation of a dual antiplatelet agent within 12 months of DES implantation were enrolled in one of the 3 study hospitals. We reviewed the clinical and procedural characteristics of the patients who developed stent thrombosis during the perioperative period. Stent thrombosis occurred in 7 cases (5.0%). The clinical outcomes of the patients with stent thrombosis were death in 5 cases and nonfatal MI in 2 cases. The patients with stent thrombosis were found to be older (64.2 +/- 9.7 versus 71.7 +/- 6.0 years, P = 0.045), to use a Taxus stent more frequently (36.6 versus 85.7%, P = 0.014), and to have a more prolonged period of discontinuation of clopidogrel (12.7 +/- 10.0 versus 51.3 +/- 33.2 days, P = 0.022) than the patients without stent thrombosis. Multivariate analysis revealed that 7 days or longer discontinuation of clopidogrel (OR 12.8, 95% CI 1.3-121.6, P = 0.021) and the use of a Taxus stent (OR 10.2, 95% CI 1.1-95.7, P = 0.043) were significant independent predictors of stent thrombosis during the perioperative period. A prolonged period of discontinuation of clopidogrel was associated with higher risk of stent thrombosis during the perioperative period. An earnest effort to continue antiplatelet therapy throughout the perioperative period can minimize the risk of stent thrombosis.