Four experimental aneurysms were treated by implantation of an endoprosthetic stent. The aneurysms were surgically created by grafting a venous pouch on the carotid artery of mongrel dogs. Aneurysm patency was assessed angiographically. Under systemic heparinization and via a transfemoral approach, the stent measuring 20 mm in length and 5 mm in diameter, was implanted in the lumen of the parent artery at the level of the aneurysmal neck. Good angiographic results were obtained immediately following implantation, showing exclusion of the aneurysm from the circulation. Patency of the parent vessel was preserved in all the experimental aneurysms treated. In one case an angiogram performed 30 days later showed the same findings with excellent tolerance of the device. The technique of endovascular treatment of experimental aneurysms by stent implantation appears feasible and safe in vivo. Further investigations are still necessary before clinical applications.