Objective: This study was undertaken to compare 1-year and 5-year results of endovascular repair of abdominal aortic aneurysm (AAA) with the Guidant/EVT bifurcated graft system with results of open repair. Methods. This was a prospective, nonrandomized, concurrent controlled study that compared results of endovascular versus open repair of AAA. The Phase II study with the EGS delivery system included 268 patients in 18 US medical centers; and the Phase III trial with the Ancure delivery system incuded 305 patients in 21 US institutions. Data were internally and externally audited and subjected to periodic review by the US Food and Drug Administration. The control group of I II patients were excluded from endovascular repair with a tube graft because of anatomic considerations, but were otherwise comparable to the experimental group. Patients in the control group underwent conventional open surgical repair concurrently with patients who underwent EGS repair in 18 US institutions. Results. Five hundred thirty-one of 573 patients (92.7%) underwent successful implantation of the Guidant/EVT bifurcated endograft. The combined major morbidity and mortality in the endograft group was 28.8%, compared with 44.1% in the open control group. Additional benefits in the endograft group included shorter hospital stay (2 days vs 6 days), less surgical blood loss (400 mL vs 800 mL), and less intensive care unit use (33% vs 94%). These early results are reported on an intent-to-treat basis; in all patients an attempt was made to treat with the endovascular graft, including those patients in whom conversion to standard open repair was necessary during the primary procedure. Three hundred nineteen patients were selected for long-term follow-up to 5 years, on the basis of date of implantation; ie, patients with the earliest implantations were followed up for 5 years. The primary purpose of long-term follow-up was to obtain data on long-term efficacy of the graft; thus only patients in whom implantation was successful were selected. No patient has experienced an-aneurysm rupture to date. Survival (Kaplan-Meier method) in the experimental group was 68.1%, compared with 77.2% in the control group (P = NS). At 60 months, 74.4% of patients (32 of 43) were free of endoleak. There were no type I or type III endoleaks remaining. Aneurysm sac diameter decreased or remained stable in 97.6% of patients (41 of 42) and increased in only I patient. During the course of long-term follow-up, post-procedural conversion to open repair was required in only 9 patients (2.8%). Conclusion: The EVT/Guidant bifurcated graft is effective in preventing AAA rupture, and long-term survival is comparable to that with open repair.