For a lmost h alf a c entury, s ynthetic v ascular g ra s have been an integral tool of vascular surgery. Although impressive success of these gra s has been made in aortic and iliac surgery, smaller diameter (≤6 mm) gra s has been a symbol for the limitations of modern biotechnology, because their long-term failure rates are still high. Small-diameter vascular gra s are used as medical implants for a number of diseases. Some exa mples o f g ra implants are coronary or periphery artery bypass gra s, pediatric vascular shunts, and vascular access gra s.