OBJECTIVE This study reports the early and midterm to long-term experience of chimney grafts (CGs) in urgent endovascular repair of complex lesions in the thoracic aorta. METHODS Twenty-nine high-risk patients (20 men) who were unfit for open repair were treated using CG technique for ruptured (n = 14) or symptomatic (n = 15) aortic lesions engaging the aortic arch itself (n = 9), the descending aorta (n = 10), or the thoracoabdominal aorta (n = 10). Twenty-two patients (76%) were treated urgently (≤24 hours) and seven were semiurgent (≤3 days). Of 41 chimneys used, 24 were placed in supra-aortic branches and 17 in visceral branches. Median follow-up (interquartile range) for the entire cohort was 2 years (0.6-3.8 years), 2.5 years (1-4 years) for 30-day survivors, and 3.5 years (1.9-6.4 years) for those who were still alive. RESULTS Four patients (14%) died ≤30 days of cerebral infarction (n = 1), visceral ischemia secondary to the initial rupture (n = 1), multiple organ failure (n = 1), or heart failure (n = 1). There were 11 late deaths (38%); however, only two deaths were related to the CG technique. The primary and secondary technical success rates were 86% (25 of 29) and 97% (28 of 29), respectively. The secondary patency rate of CGs was 98%. Seventeen (68%) of the aortic lesions shrank significantly. Three patients (10%) had primary type I endoleak and another three (10%) had secondary type I endoleak. The endoleaks were managed with Onyx (ev3 Endovascular, Inc, Plymouth, Minn) or coil embolization (n = 2), restenting (n = 1), and conversion to open repair (n = 2). One secondary endoleak is still under observation after >20 months. All primary endoleaks and one secondary endoleak originated from CGs in the brachiocephalic trunk (4 of 6 [67%]). CONCLUSIONS The midterm to long-term results of the CG technique for urgent and complex lesions of the thoracic aorta in high-risk patients are promising, with low early mortality and long durability of the CGs. More patients with longer follow-up are still needed.