Introduction: Patients with abdominal aortic aneurysms (AAA) undergoing infrarenal EVAR with larger device diameters (34- to 36-mm) have been found to have worse outcomes due to proximal fixation failure and need for reintervention. We sought to examine outcomes relating to standard fenestrated repair (FEVAR) with larger device diameters, and investigate whether a similar relationship exists. Methods: A retrospective review was performed of a prospectively maintained, single institution database of patients treated with the Cook ZFEN device between 2012 and 2018. Patient demographics, anatomic and device information, and procedural and follow-up data were analyzed. Outcomes were stratified by device diameter into normal-diameter (< 32 mm) and large-diameter (34-36 mm). The primary endpoints examined were need for reintervention and composite type I/III endoleak. Results: One hundred consecutive patients treated with the ZFEN device were identified for inclusion. Overall mean age was 73.6 years and mean aortic diameter was 59.1 mm. Mean follow-up was 22 months. A total of 26 (26%) patients were treated with large-diameter devices. Number of target vessel per patient was 2.8 in both group. Infrarenal neck length and diameter were significantly different in the large-diameter and normal-diameter patients, respectively (2.6mm vs 4.7mm (P< .01) and 30.1mm vs 23.4mm (P< .01)). New seal length was similar among groups (large-diameter: 32.4mm, normal-diameter: 29.7mm, (P=.12)). Percent graft oversizing was lower in the large-diameter cohort (19% vs 24%; P=.006). No difference was seen in overall mortality at 30-days (0% vs 2%; P=.4) or at latest follow up (6% vs 14%; P=.6). Reinterventions were significantly higher in the large-diameter cohort (12/26, 46.2%) than the normal-diameter cohort (13/74, 17.6%; P=.002). Larger neck diameter (HR 1.08, 95% CI 1.1-1.17) and device diameter (HR 1.19, 95% CI 1.04-1.37) were associated with reintervention on univariate, but not multivariate, analysis. Neck length was not associated with need for reintervention (HR 0.85, 95% CI 0.71-1.01). The composite endpoint of type I/III endoleak was found to be higher in the large-diameter cohort (15.4% vs. 2.7%; P=.004). Conclusion: FEVAR requiring 34- or 36-mm device diameters is associated with an increased risk of composite type I/III endoleak and reintervention. Patients undergoing standard fenestrated repair requiring larger diameter devices should be monitored more closely for these complications, and consideration should be given for more proximal repair or open repair if feasible. Disclosure: Nothing to disclose