At the present time plastic arterial prostheses are utilized widely in reconstruction of the resected aorta. Fabricated Teflon and Dacron prostheses have proved their superiority over homografts, and most of those which are commercially available provide acceptable aortic substitutes. Individual preference for a specific prosthesis depends upon availability, uniformity, handling properties, and the surgeon's experience in their use. Although the factors influencing arteriogenesis, proper endothelialization, and long-term patency have been the subject of intensive laboratory study, the relative merits and safety of the various prostheses must be established ultimately by careful clinical follow-up. Wesolowski4 demonstrated that porosity plays an important part in the arteriogenesis and long-term patency of arterial prostheses. Grafts which are impermeable to blood at the time of implantation do not permit the subsequent ingrowth of mesenchymal cells which is necessary for uniform endothelialization and satisfactory bonding of the internal lining of the prosthesis. Porosity also influences