OBJECTIVE. The aim of this study was to investigate the association between the tortuosity of the targeted aortic segment (TAS) for stent-graft implantation and distal stent-graft–induced new entry (SINE) after thoracic endovascular aortic repair (TEVAR) for aortic dissection or intramural hematoma. MATERIALS AND METHODS. We retrospectively analyzed data from 70 patients who underwent TEVAR using a single stent-graft between 2006 and 2016, and the tortuosity index of the TAS was measured. The patients were divided into high and low TAS tortuosity groups according to the median value of the tortuosity index. The incidence of distal SINE was compared between the two groups. RESULTS. The cumulative incidence of distal SINE at 2 years after TEVAR was 39% in patients in the high TAS tortuosity group and 7% in patients in the low TAS tortuosity group. The incidence of distal SINE was higher in patients in the high TAS tortuosity group than in those in the low TAS tortuosity group (p < 0.01, log-rank test). Multivariate Cox regression showed a higher risk of distal SINE in the high TAS tortuosity group (adjusted hazard ratio, 4.56 [95% CI, 1.40–14.86]; p = 0.01). CONCLUSION. Patients with high TAS tortuosity have a higher incidence of distal SINE after TEVAR. More caution must be exercised during follow-up of patients with high TAS tortuosity after TEVAR.