Using our modification of the vein patch technique, we created 16 aneurysms in the common carotid arteries of dogs. After a stabilizing and healing period, these aneurysms were treated using percutaneous catheter techniques. Coaxial microcatheters were placed into the aneurysms, and a mixture of isobutyl 2-cyanoacrylate and tantalum dust was infused through the microcatheter using real time fluoroscopic control. Fifteen of the 16 aneurysms were successfully occluded; 1 was a failure because of total occlusion of the carotid artery. One human facial artery aneurysm was similarly treated. The ease and technical details of the treatment are discussed. Although the results are encouraging, we believe that it would be prudent to broaden the animal experimentation rather than to begin human use. Because no experimental aneurysm models are yet physiological, our results must be applied with caution to human intracranial aneurysms.