Abstract: A cardiac valve prosthesis comprises an annular frame and a valve sleeve with a plurality of valve flaps which are forced apart by the blood passing through the prosthesis in one direction and which are mutually coapted by blood flow in the opposite direction. The frame of the prosthesis includes a rigid or semi-rigid stent constituted by a tubular body with a ring of apertures and with first and second end edges which, in the implanted position of the prosthesis, are respectively upstream and downstream with respect to the direction of flow of the blood through the prosthesis. Biocompatible textile completely covers the rigid stent: the covering has associated suture stitches some of which extend through the apertures of the said ring to attach the covering to the stent itself.