BACKGROUND: Physician modified endografts (PMEGs) have been widely used in the treatment of complex abdominal aortic aneurysm and thoracoabdominal aortic aneurysm, however, previous data are limited to small single center studies and robust data on safety and effectiveness of PMEGs are lacking. We aimed to perform an international multicenter study analyzing the outcomes of PMEGs in complex abdominal aortic aneurysms and thoracoabdominal aortic aneurysms. METHODS: An international multicenter single-arm cohort study was performed analyzing the outcomes of PMEGs in the treatment of elective, symptomatic, and ruptured complex abdominal aortic aneurysms and thoracoabdominal aortic aneurysms. Variables and outcomes were defined according to the Society for Vascular Surgery reporting standards. Device modification and procedure details were collected and analyzed. Efficacy outcomes included technical success and safety outcomes included major adverse events and 30-day mortality. Follow-up outcomes included reinterventions, endoleaks, target vessel patency rates and overall and aortic-related mortality. Multivariable analysis was performed aiming at identifying predictors of technical success, 30-day mortality, and major adverse events. RESULTS: Overall, 1274 patients were included in the study from 19 centers. Median age was 74 (IQR, 68–79), and 75.7% were men; 45.7% were complex abdominal aortic aneurysms, and 54.3% were thoracoabdominal aortic aneurysms; 65.5% patients presented electively, 24.6% were symptomatic, and 9.9% were ruptured. Most patients (83.1%) were submitted to a fenestrated repair, 3.6% to branched repair, and 13.4% to a combined fenestrated and branched repair. Most patients (85.8%) had ≥3 target vessels included. The overall technical success was 94% (94% in elective, 93.4% in symptomatic, and 95.1% in ruptured cases). Thirty-day mortality was 5.8% (4.1% in elective, 7.6% in symptomatic, and 12.7% in ruptured aneurysms). Major adverse events occurred in 25.2% of cases (23.1% in elective, 27.8% in symptomatic, and 30.3% in ruptured aneurysms). Median follow-up was 21 months (5.6–50.6). Freedom from reintervention was 73.8%, 61.8%, and 51.4% at 1, 3, and 5 years; primary target vessel patency was 96.9%, 93.6%, and 90.3%. Overall survival and freedom from aortic-related mortality was 82.4%/92.9%, 69.9%/91.6%, and 55.0%/89.1% at 1, 3, and 5 years. CONCLUSIONS: PMEGs were a safe and effective treatment option for elective, symptomatic, and ruptured complex aortic aneurysms. Long-term data and future prospective studies are needed for more robust and detailed analysis.