OBJECTIVE Open repair of complex aortic aneurysms is frequently not an option for octogenarians because of prohibitive surgical risks. This study aimed to analyze the outcomes of fenestrated-branched endovascular aortic repair (F-BEVAR) in octogenarians (≥80 years old) compared with nonoctogenarians (<80 years old). METHODS We reviewed 893 patients with pararenal or extent I to V thoracoabdominal aneurysms, enrolled in six prospective physician-sponsored investigational device exemption studies from 2012 to 2018. All patients were treated with either company-manufactured off-the-shelf or patient-specific F-BEVAR stent grafts. Data analyzed included demographics, cardiovascular risk factors, history of active cancer, American Society of Anesthesiologists classification, aortic anatomy characteristics, and procedural data. End points included mortality, major adverse events (all-cause mortality, stroke, paralysis, acute kidney injury [RIFLE criteria], dialysis, myocardial infarction, respiratory failure, and bowel ischemia), technical success, hospital length of stay, target artery instability (occlusion/stenosis, endoleak, rupture or death), and secondary interventions. RESULTS During the study period, 195 octogenarian patients (22%) and 698 (78%) nonoctogenarian patients were treated with F-BEVAR. Octogenarians presented more frequently with a history of cancer (17% vs 11%; P = .01), whereas nonoctogenarians more frequently had hyperlipidemia (76% vs 65%; P = .003), chronic obstructive pulmonary disease (42% vs 33%; P = .04) and American Society of Anesthesiologists class III to V (78% vs 70%; P = .02). Male sex was similar between groups (68% [octogenarians] vs 70% [nonoctogenarians]; P = .62). Octogenarians had a larger mean aneurysm diameter (67 ± 1 mm vs 65 ± 1 mm; P = .002). The thoracoabdominal classification and the use of upper extremity access were similar between groups. Estimated blood loss was also similar (484 ± 454 mL [octogenarian] vs 416 ± 457 mL [nonoctogenarian]; P = .07). Octogenarians had an increased mean number of vessels incorporated into the repair (3.1 ± 1.4 vs 2.7 ± 1.7; P < .001). The technical success rate was 99% for octogenarians and 97% for nonoctogenarians (P = .19). The 30-day mortality rate was 0.5% for octogenarians and 1.3% for the nonoctogenarians (P = .70). Major adverse events (9.2% vs 9.7%), types I/III endoleak (4.6% vs 2.4%) access complication (3.1% vs 3.3%), and length of stay (8.2 ± 27 days vs 5.7 ± 6.3 days) were all similar between the groups. Freedom from target artery instability and freedom from secondary interventions at 3 years were similar between the groups. Octogenarian survival was lower at 3 years compared with nonoctogenarians on univariate analysis (log-rank P < .01) and on multivariable analysis after adjusting for history of active cancer, hyperlipidemia, and chronic obstructive pulmonary disease. CONCLUSIONS Despite small differences in demographics, anatomic factors, and procedural data, F-BEVAR was safe and effective with nearly identical early outcomes in octogenarians in these experienced aortic centers. More extensive clinical experience and longer follow-up are needed to better delineate factors impacting longer term mortality.