Background : There were limited data about the procedural success rate and its predictive factors in percutaneous coronary intervention (PCI) for chronic total occusion (CTO). This study was designed to identify the predictive factors of procedural success among lesion and procedural characteristics. Method : Between January 2006 and June 2008, 171 consecutive patients underwent PCI for the CTO at Catholic University Hospitals. These patients were analyzed in terms of the lesion and procedural characteristics, the success rate, predictors of procedural success, and clinical outcome. The study population was grouped by procedural success and failure. In-hospital and long-term clinical outcomes were compared in each group. Result :The procedural success rate was 80.7%. The wiring method of penetrating CTO was all most antegrade approach except for 2 patients. Multivariate regression analysis showed that the success rate was significantly influenced by the following variables: extent of the coronary artery disease (p=0.05), morphology of occlusion (p=0.005), calcification of the lesion (p<0.0001), bridging collaterals (p=0.012). And the other factors were BNP and pro- BNP (p<0.0001). The total number of MACE was 29 (1 In-hospital death, 6 target lesion revascularization, 11 target lesion revascularization, 3 stent thrombosis, 8 congestive heart failure). There was no difference of clinical outcome between the success group and the failure group success group:n=24(15.6%) vs failure group:n=5(9.1%), p=0.418. Conclusion : In this study, a relatively high success rate of PCI for CTO was obtained. The predictive factors of successful PCI for CTO were less extent of vessel, tapered pattern of occlusion, no calcification of the lesion, no bridging collaterals, and the low level of BNP and pro-BNP.