This limited study addressed the feasibility of treating aneurysms with a new transcatheter endoprosthesis. Aortic aneurysms were experimentally created in six dogs and subsequently bridged with nylon-covered, self-expanding metallic stents. The dogs were followed up for as long as 7 months (median, 22 weeks). In each dog, the graft effectively reconstituted the aortic lumen, excluding the aneurysm. One dog exhibited minimal (less than 1-mm) residual dilatation at the site of the aneurysm 7 months after graft placement. The nylon material acted as a support and template for neointimal encasement, enabling the formation of a new vascular lumen. It also remained porous at the origin of aortic side branches, preserving the visceral blood supply. One of the endovascular grafts failed to expand completely at its distal end, which promoted thrombus formation within the graft and resulted in the occlusion of both renal arteries. The dog was found comatose 48 hours after graft placement and was killed at that time.