Despite improving techniques for opening chronic total occlusions (CTOs), the benefit of successful recanalization of the artery remains unclear. The aims of this study were to investigate the safety and efficacy of percutaneous coronary intervention for "true" CTO, defined by Thrombolysis In Myocardial Infarction (TIMI) flow grade 0 and duration > or =3 months, and to compare the outcome of successful versus failed procedures. A cohort of 172 consecutive patients with de novo CTOs of native vessels confirmed by angiographic review in which percutaneous coronary interventions were attempted was studied. End points included angiographic success, in-hospital complications, and long-term major adverse cardiac events. Technical success was obtained in 73.8% of CTO lesions (127 of 172). No deaths or nonfatal Q-wave myocardial infarctions occurred in the hospital. Repeat percutaneous coronary interventions in the hospital were required in 1.6% of patients (2 of 127) in whom the CTOs were initially opened. Perforation during the initial failed attempts occurred in 6.7% of patients (3 of 45). One patient required operative repair. After an average follow-up period of 2 years, patients with successful procedures experienced similar incidences of cardiac death and nonfatal Q-wave myocardial infarctions as did patients with failed procedures (5.3% and 4.9%, respectively, p = 0.3). Patients with successfully opened arteries required target vessel revascularization more frequently, but this did not reach statistical significance (18.8% vs 0%, p = 0.06). In conclusion, attempts to open CTOs with the devices available at the time of this registry were accompanied by a significant risk for perforation. Furthermore, successful recanalization did not translate into a reduction in 2-year mortality or nonfatal Q-wave myocardial infarctions compared with patients with failed procedures.