Purpose: To evaluate the incidence and reasons for secondary procedures in patients treated with iliac branch devices (IBDs) for isolated iliac aneurysm or aortoiliac aneurysms involving the iliac bifurcation. Methods: Between January 2005 and December 2015, 575 surgical-high-risk patients (mean age 72.0±8.4 years; 558 men) with isolated iliac aneurysms (n=79) or aortoiliac aneurysms involving the iliac bifurcation (n=496) were treated with placement of 650 ZBIS or Gore IBDs (75 bilateral) in 6 European centers. The primary outcome was procedure-related reinterventions for occlusion or high-grade (>70%) stenosis of the bridging device, occlusion of the ipsilateral common or external iliac artery (EIA), type I/III endoleak, rupture, or infection following IBD implantation. Clinical and radiological data were analyzed based on preset definitions of comorbidities, aneurysm morphology, intraoperative variables, and follow-up strategies. Results: Nine (1.6%) reinterventions were performed within 30 days for occlusion or endoleak. Among 10 (1.5%) occluded EIAs ipsilateral to a deployed IBD, 6 underwent a reintervention with additional stent placement after thrombolysis (n=4) or a femorofemoral or iliofemoral crossover bypass (n=2). Three of 14 patients with early type I endoleak had a reintervention for an insufficient proximal sealing zone (stent-grafts in 2 common iliac arteries and 1 bifurcated endograft). Mean clinical and radiological follow-up were 32.6±9.9 and 29.8±21.1 months, respectively. Forty-two (7.3%) patients underwent reinterventions in the follow-up period. The overall postoperative reintervention rate was 8.9%. Both external and common iliac segments occluded in 30 (4.6%) IBDs; 2 patients had a crossover bypass and 14 were treated with endovascular techniques. In the other 14 patients, no specific treatment was performed. Seven (1.2%) patients with isolated EIA occlusion were treated during follow-up. Nineteen of the overall 28 patients with type I endoleak underwent endovascular repair. The other 9 were under radiological surveillance due to less significant (<5 mm) sac increase. No reintervention was performed to recanalize 11 (1.6%) occluded internal iliac arteries. Conclusion: Midterm experience with placement of IBDs is associated with a low incidence of secondary procedures due to type I endoleaks and occlusions. The main reasons for reinterventions seem to be short proximal sealing zone and poor conformability of the ZBIS device in elongated EIAs.