Endovascular grafts (EVGs) have been proposed as a treatment for a variety of vascular diseases; however, the impact of EVGs on graft healing has not been fully evaluated. The aim of this study is to compare anastomotic intimal hyperplasia (AIH) and endothelialization in EVGs and conventional bypass grafts (CGs). Seven mongrel dogs received an EVG in one iliac artery and a CG in the other iliac artery using 5 mm x 4 cm polytetrafluoroethylene graft. The EVG was secured to the native vessel wall, with balloon expandable stents at either ends of the graft. CGs were anastomosed using running sutures. Intra-vascular ultrasound was performed at the time of sacrifice (8 weeks) to determine percentage of stenosis at the distal anastomosis. Specimens were divided longitudinally for light microscopic analysis (thickness of distal AIH) an scanning electron microscopic studies (percentage of endothelial coverage of the graft). Percentage of stenosis at the distal anastomosis was significantly higher EVGs compared with CGs (28.2 ± 18.2%; versus 1.8 ± 2.8% P < 0.01) due to significantly greater mean intimal thickness in the EVGs (44.1 ± 101.1 μ versus 82.4 ± 41.9 μ; P < 0.01). The total percentage of area covered by endothelial cells was also significantly greater in EVGs compared with CGs (80.5 ± 37.5% versus 30.3 ± 37.1%; P < 0.05). Intraluminal location enhanced endothelialization of the polytetrafluoroethylene graft; however, it also resulted in greater AIH. Further device refinements including stent design may be required to maximize the potential of these endovascular procedures.