Background : With improvements in technology and techniques, intravascular ultrasound (IVUS) guided percutaneous coronary intervention (PCI) provided optimal stent placement and improved clinical outcomes. However, chronic total occlusion (CTO) recanalizations remain extremely challenging procedures and the studies looking at the impact of IVUS on CTO intervention are very limited. Methods: From retrospective CTO registry, a total of 2,971 patients with CTO who underwent percutaneous coronary intervention (PCI) were enrolled in this study and then classified into two groups according to the use of IVUS for CTO intervention; IVUS group (n=774), defined as the use of IVUS during the intervention, vs. Non-IVUS group (n=2194). Results: Median follow up duration was 701 days (interquartile range: 360, 748). Baseline characteristics were similar between between IVUS and non-IVUS group except more current smoking patients are in non-IVUS group (31.6% vs. 36.2%, p=0.034). IVUS group showed significantly higher technical success rates than non-IVUS group (94.7% vs. 78.2%). On Kaplan-Meier analysis, both groups did not show any different in death (p=0.717), MI (p=0.402) or the composite of death or MI (p=0.494). On 1:1 matching with propensity score adjusted by age, gender, hypertension, diabetes, previous MI, heart failure and acute coronary syndrome, both group did not show significant difference in the clinical outcomes. Conclusion: The potential advantage of IVUS-guided intervention were not shown in this registry. However, randomized clinical trial could prove the efficacy of IVUS-guided CTO intervention