Background and Objectives : The SYNTAX score (SXscore) has been proposed as a valuable angiographic scoring system to assist in patient selection and risk stratification of patients undergoing percuatenous coronary intervention (PCI) or surgery for multivessel coronary artery disease. However, the prognostic value of SXscore has a limitation in the real-world settings in which technical improvements and development of newer drug-eluting stent (DES) have improved clinical long-term outcomes. Furthermore, SXscore was not applicable for prior bypass or angioplasty vessels. The purpose of this study is to assess whether the SXscore is independent prognostic factor in patients undergoing PCI for multivessel disease in the present DES era. Subjects and Methods : We applied the SXscore in 828 patients who underwent PCI for 2- or 3-vessel disease, with/without left main disease and previous PCI. Median clinical follow-up duration was 35 months (interquartile range: 29-42 months) after the index PCI. The primary endpoint was the composite of major adverse cardiac event (MACE) including all-cause of death, non-fatal myocardial infarction (MI), or any repeat revascularization. Potential risk factor effects on MACE were evaluated using Cox regresseion. Results : The median SXscore was 21.0 (intertertile range: 16.0-25.0). The MACE occurred in 193 patients (23.3%) during follow-up periods. The SXscore did not predicted the occurrence of MACE, with patients in the highest SXscore tertile not having a significantly higher MACE rate than patients in the lower two tertiles (25.8% versus 22.1%, P=0.234). Complete revascularization (CR) was achieved in 391 patients (47.2%), with the patients in the highest SXscore tertile having significantly lower CR rate than the patients in the lower two tertiles (39.0% versus 51.2%, P=0.001). By multivariate Cox regression analysis, incomplete revascularization (IR) (HR, 1.79; 95% CI, 1.33 to 2.41; P < 0.001), left ventricular systolic dysfunction (ejection fraction < 40%) (HR, 1.87; 95% CI, 1.22 to 2.86; P=0.004), and non-ST-segment elevation acute coronary syndrome (HR, 1.43; 95% CI, 1.08 to 1.91; P=0.014) were independent predictors of MACE. In the subgroup analysis for patients in highest SXscore tertile, IR was only independent predictor for MACE (HR, 1.86; 95% CI,1.09 to 3.19; P=0.024). Conclusion : The prognostic value of SXscore in patients undergoing PCI for multivessel disease is lacking in the real-world settings. CR is independently associated with long-term clinical outcomes. If CR could be achieved despite high SXscore, it seems to promise favorable clinical outcomes. Key Words : SYNTAX score; Revascularization; Multivessel disease.