The plastic substitution of the aorta and its large branches may be considered largely solved today. For this purpose preference is given to highly porous, thin-walled double velour prostheses. The search for a biocompatible plastic substitute for small caliber arteries and the large veins of the body (portal vein, vena cava, iliac veins) is proceeding in two directions at the present time: on the one hand towards optimized bioprostheses and on the other hand towards plastics which apply the principle of microporosity or impermeability with the creation of antithrombogenic inner surfaces. In this respect expanded polytetrafluoroethylene and coating with carbon are very promising.