The objective of this study was to report the short- and medium-term outcome of surgeon-modified fenestrated endovascular aneurysm repair (SM-FEVAR) for acute complex aortic aneurysms. Interrogation of a prospectively maintained database identified consecutive patients who underwent SM-FEVAR for acute complex aortic aneurysms (including mycotic aneurysms treated with rifampicin-soaked endografts) in a single institution between October 2009 and November 2018. A total of 54 patients (37 men; median age, 73 years [range, 50-85 years]; aneurysm diameter, 76 mm [interquartile range, 58-90 mm]) with acute thoracoabdominal aortic aneurysms (n = 50; 40 symptomatic, 10 ruptured; 19 extent I-III, 31 extent IV) or symptomatic type IA endoleaks after infrarenal endovascular aneurysm repair (n = 4) underwent SM-FEVAR. Seven of the patients had adjunct chimney and periscope stent grafts or surgical bypasses. A total of 187 vessels (mean, 3.4 [range, 1-5] per patient) were targeted for preservation; nine occluded intraoperatively or within 30 days.