Abstract: A prosthesis for a blood vessel comprises an implantable tubular cylindrical element of biocompatible material, affording a pair of rigid rings positioned one at either end, that can be inserted into a diseased section of the opened vessel with the rings offered in direct contact to corresponding healthy cylindrical portions, also, a pair of first spiral wound locating elements respectively associated with and encircling the rings through a circumferential distance of no less than 360.degree., each of which is ensheathed freely in its turn by a second spiral wound stitching element having a sharp point; the second spiral wound element is rotated helically about the first spiral wound element and caused thus to advance along its own longitudinal axis, with the result that the rigid ring becomes securely anchored as the point penetrates the wall of the vessel, progressively pinning the cylindrical portion to a given depth between the two spiral wound elements.