Late open conversion following endovascular aneurysm repair (EVAR) represents a failure of therapy, used to treat complications refractory to secondary endovascular intervention. With liberalization of EVAR and expansion to populations outside of instructions for use (IFU), it is imperative to better understand predictors and to prevent this outcome. The objective of this study was to understand the patterns of presentation, graft-specific differences, outcomes of interventions, and relationship to IFU adherence among patients who underwent late open conversion of EVAR. Records of 1038 consecutive patients who underwent EVAR at The Ottawa Hospital between October 2000 and May 2015 were reviewed from a prospective database. Patients requiring conversion to open repair >1 month after implantation were identified. Patients who underwent fenestrated, branched, or thoracic endovascular repair were excluded. Variables analyzed included date of interventions, adherence to IFU, graft type, interval to open conversion surgery, reason for removal, operative technique, length of stay, hospital complications, and death. A total of 16 patients underwent EVAR that required subsequent late conversion to open repair. Initial grafts implanted included Medtronic (Santa Rosa, Calif) Talent (eight patients, 50.0%), Medtronic Endurant (three patients, 18.8%), Cook (Bloomington, Ind) Zenith (four patients, 25.0%), and Terumo (Somerset, NJ) Anaconda (one patient, 6.2%). Average time to intervention was 3.3 ± 2.5 years, and this interval decreased during the study period (4.6 ± 3.0 years for EVARs before 2007 vs 2.89 ± 1.37 years for EVARs after 2009). Indications for conversion were graft infection in four patients (25%), aneurysm rupture in two patients (12.5%), endograft migration in three patients (18.8%), sac expansion secondary to type Ia endoleak in three patients (18.8%), sac expansion secondary to type II endoleak in two patients (12.5%), and sac expansion without detectable endoleak in two patients (12.5%). Nine patients (56.2%) underwent open conversion by stent graft explantation with in situ graft reconstruction; the remaining seven patients were treated with open cerclage of the aneurysm sac around the device. The 30-day mortality was 18.8%. Major in-hospital complications occurred in 10 patients (62.5%). An additional two patients (12.5%) required postconversion surgical reintervention. During initial EVAR, operators were adherent to device IFU in seven cases (43.8%), which is markedly lower than IFU adherence rates of 88.0% among uncomplicated EVARs in our database. Conversion to open repair following EVAR is associated with significant morbidity and mortality. The rate of operator adherence to IFU at time of initial EVAR in this cohort of open conversions is markedly low in comparison to the overall EVAR cohort. The decreasing interval to open conversion is concerning and may be a reflection of increasing liberalization of EVAR to populations outside of IFU.