Background: Despite improving techniques for opening chronic total occlusions (CTOs), the benefit of successful recanalization of the artery remains unclear. Previous several studies have showed controversy about the benefit of successful recanalization in CTO. The aims of this study were to investigate the long term clinical outcomes of ���true��� CTO vessel for 3 years, according to revascularization success. Methods: From February 2003 to March 2006, total 364 consecutive patients with ���true��� were enrolled in Asan Medical Center & Bucheon SoonChunHyang Hospital. A ���true��� CTO was defined as Thrombolysis In Myocardial Infarction (TIMI) flow grade O on angiography and duration ���3 months. Patients were divided into 2 groups with regard to the success (n=276) or failure to revascularization of occluded artery/no trial with only medical therapy (n=88). The primary endpoint was composite of cardiac death/Myocardial infarction/Target Vessel Revascularization/Cardiac re-hospitalization. Cardiac re-hospitalization was defined as re-admission due to recurrent angina or heart failure despite optimal medical therapy. Results: The median follow-up duration was 1322 days. The 3-year incidences of composite of clinical outcomes were 8.7% in success group and 20.6% in failed PCI/medical group, respectively (long-rank p<0.001). After multivariable adjustment, composite of clinical outcomes was significantly higher in failed PCI/medical therapy group (Adjusted HR 2.24, 95% Confidence Interval: 1.26-3.57, p=0.006). Conclusion A successful recanalization of ���true��� CTO showed improved long-term clinical outcomes for 3 years compared with patients with failed procedures or only medical therapy.