Background Although drug-eluting stents (DES) have dramatically reduced the rate of restenosis, concerns have been raised regarding the risk of stent thrombosis (ST) with the unrestricted use of these stents. Therefore, we investigated the clinical characteristics, predictors, and outcomes of ST after successful DES implantation in Koreans. Method This was a multicenter study, where we collected data of consecutive ST patients who underwent DES implantation from May, 2004, through April, 2006 at 10 medical centers. All information were sent to a core center and the clinical, angiographic and procedural characteristics of ST patients were compared with a control group of 2,474 patients in a core center who had up to 18 months of clinical follow-up. Possible ST as well as angiographically proven ST were defined as ST in this study. Results During the study period, a total of 93 patients had 96 cases of ST(Cypher:51(53%), TAXUS: 45(47%)). ST occurred acutely in 6 cases (6%), subacutely(���30 days) in 52 cases (54%), and late(>30 days) in 38 cases(40%). The mean duration to ST from the stent implantation was 6.4짹5.8 days in subacute and 319짹219 days in late ST. Nine patients had discontinued clopidogrel prematurely(9%). Seventy(75%) patients presenting with ST were treated with percutaneous coronary intervention and 7(8%), with CABG. Among the 93 patients, 16 died (case fatality rate,17%). By multivariate analysis, independent predictors of ST were bifurcating lesion(OR 7.05;95% CI, 4.42-11.3;P<0.0001), heavy vascular calcification(OR 5.91;95% CI, 3.1-11.3;P<0.0001), initial diagnosis of AMI(OR 4.69;95% CI, 3.01-7.32;P<0.0001), small stent diameter(OR per 1mm decrease 2.40;95% CI, 1.18-4.93;P=0.016), multivessel disease(MVD)(OR 1.88;95% CI, 1.17-3.04;P=0.010), young age(OR per year decrease 1.033; 95% CI, 1.012-1.054;P=0.002) and long stent length (OR per 1mm increase 1.013;95% CI, 1.00-1.026;P=0.045). Conclusions In a study involving 10 centers in Korea, nearly half of the stent thrombosis cases occurred in the late period. Bifurcating lesion, heavy vascular calcification, AMI, MVD, young age, long stent length and small stent diameter were identified as predictors of ST.