Objective: Traditional open surgical repair of thoracoabdominal aortic aneurysms (TAAAs) has historically resulted in 30-day mortality rates ranging from 6% to 20%, depending on the Crawford anatomic extent. Although short-term survival is important, long-term survival is essential for patients to benefit from these often elective and potentially morbid procedures. The aneurysm extent affects the long-term survival after open repair; however, effect on endovascular repair is unknown and could influence the decision process for repair. We evaluated the association between aneurysm extent and survival and identified patient and perioperative factors associated with mortality after endovascular repair. Methods: A retrospective cohort of patients treated for TAAAs recorded in the Society for Vascular Surgery Vascular Quality Initiative thoracic and complex endovascular aneurysm repair registry were evaluated. All patients treated for asymptomatic degenerative aneurysms from 2010 to 2019 were included. Crawford extent I to V was defined according to the proximal and distal landing zones documented in the registry. Patients without extension into the visceral aorta were used for comparison and categorized as having extent 0a or 0b, depending on the distal landing zone in the thoracic aorta. Kaplan-Meier plots were used to estimate survival, and Cox proportional hazard regression models were created to identify the predictors of mortality. Results: From 2010 to 2019, 15,333 patients were entered into the registry, of whom 2062 met the inclusion criteria. The Crawford extent was 0a for 379, 0b for 848, I for 81, II for 98, III for 130, IV for 454, and V for 72. Three groups were created in accordance with the similar outcomes noted on a preliminary analysis: (1) extent 0a and 0b; (2) extent I, II, and III; and (3) extent IV and V. The mean survival time for the extent 0a and 0b group was 70.7 ± 1.43 months and was 48.6 ± 1.65 months for the extent I, II, and III group and 57.6 ± 1.24 months for the extent IV and V group. The corresponding 1-year mortality was 8.4%, 18.4%, and 7.8%. Cox regression analysis identified the following preoperative factors were associated with mortality: chronic obstructive pulmonary disease (odds ratio [OR], 1.70; P <.001), Crawford extent I to III (OR, 1.64; P =.015), preexisting chronic kidney disease (OR, 1.37; P =.024), and age per year (OR, 1.03; P <.001). A number of postoperative factors were also associated with mortality. Conclusions: Similar to open TAAA repair, patients with more extensive aortic disease treated with endovascular repair had worse 1-year and long-term survival. The extent of aortic disease and anticipated postoperative survival should factor prominently into the surgical decision-making process for elective endovascular TAAA repair.