Ivalon (formalinized polyvinyl) sponge has been used as a prosthesis to fill the postpneumonectomy hemithorax,13 as a wrapping for aortic aneurysms,14 to collapse the tuberculous lung,3,5 to improve the female bust contour,15 as a space-occupying material in surgery of the paranasal sinuses,21 to prevent sutures from cutting through the fragile tissues of the aortic sinuses1 and liver parenchyma,10 and as a chest-wall prosthesis.12,23 Shumway, Gliedman, and Lewis22 first reported the formation of arterial grafts by molding and compressing Ivalon. Their preliminary report was highly encouraging. Kirklin9 also was an early investigator of Ivalon grafts in patients needing arterial reconstruction. Rob19 stated that the molded compressed Ivalon tubes were superior to homografts for large artery replacement. The authors began the investigation of this prosthesis in June, 1955. It soon became obvious that careful precise construction of the graft (Fig. 1)