Temporary venous transfemoral or trans-saphena endoprosthesis for a total vascular exclusion of the liver, to be used in most critical surgical operations like in example in major hepatectomy and in hepatic trauma with relevant venous damage, comprising: - an endovenous catheter, with a millimetric scale, having the shape of a cylinder extended longitudinally, being flexible in order to be inserted from the femoral vein or saphena vein directed to the inferior caval vein; the endovenous catheter has a diameter in the order of the inner diameter of the same femoral veln or saphena vein; - a cylindrical element placed at the distal part of said endovenous catheter; the lower side of the cylindrical element in the part close to said catheter is oblique and has a rounded border; - a mechanism of radial expansion of said cylindrical element activated under control of a specific command device, so that, under control of an operator, the endovenous catheter is firstly installed by insertion from the femoral vein or saphena vein directed to the caval vein, with the cylindrical element placed in the caval tract of the upper hepatic veins, and then said mechanism of radial expansion of said cylindrical element is activated so that the lateral walls bond and close the holes connecting the upper hepatic veins to the inferior caval vein, permitting the blood to flow inside the same cylindrical element and preventing at the same time a return of blood to the liver; in such a way, with a simultaneous Pringle maneuver that stops the blood going to the liver, a total vascular exclusion of the liver is achieved, wherein: - said endovenous catheter comprises a hollow cylindrical element; - said cylindrical element is composed of a layer of flexible material, preferably flat and having a triangular or squared shape, connected and rolled up on a supporting element that is directed along the longitudinal axis of the endovenous catheter; the supporting element extends itself up to the proximal part of the endovenous catheter, where it is connected to a control wheel; the supporting element, with the layer of material rolled on it, is free to translate forward and backward inside said hollow cylindrical element; - said mechanism of radial expansion of said cylindrical element includes a piston device that is activated by said control wheel: a rotary motion in one sense - clockwise or counter clockwise - causes the supporting element to move forward outside of said hollow cylindrical element with a progressive unrolling of said layer of material and therefore the expansion of said radial surface; a rotary motion in the opposite sense - counter clockwise or clockwise - causes the supporting element to move backward inside of said hollow cylindrical element with a progressive rolling of said layer of material, and therefore the compression of said radial surface. - an endovenous catheter, with a millimetric scale, having the shape of a cylinder extended longitudinally, being flexible in order to be inserted from the femoral vein or saphena vein directed to the inferior caval vein; the endovenous catheter has a diameter in the order of the inner diameter of the same femoral veln or saphena vein; - a cylindrical element placed at the distal part of said endovenous catheter; the lower side of the cylindrical element in the part close to said catheter is oblique and has a rounded border; - a mechanism of radial expansion of said cylindrical element activated under control of a specific command device, so that, under control of an operator, the endovenous catheter is firstly installed by insertion from the femoral vein or saphena vein directed to the caval vein, with the cylindrical element placed in the caval tract of the upper hepatic veins, and then said mechanism of radial expansion of said cylindrical element is activated so that the lateral walls bond and close the holes connecting the upper hepatic veins to the inferior caval vein, permitting the blood to flow inside the same cylindrical element and preventing at the same time a return of blood to the liver; in such a way, with a simultaneous Pringle maneuver that stops the blood going to the liver, a total vascular exclusion of the liver is achieved, wherein: - said endovenous catheter comprises a hollow cylindrical element; - said cylindrical element is composed of a layer of flexible material, preferably flat and having a triangular or squared shape, connected and rolled up on a supporting element that is directed along the longitudinal axis of the endovenous catheter; the supporting element extends itself up to the proximal part of the endovenous catheter, where it is connected to a control wheel; the supporting element, with the layer of material rolled on it, is free to translate forward and backward inside said hollow cylindrical element; - said mechanism of radial expansion of said cylindrical element includes a piston device that is activated by said control wheel: a rotary motion in one sense - clockwise or counter clockwise - causes the supporting element to move forward outside of said hollow cylindrical element with a progressive unrolling of said layer of material and therefore the expansion of said radial surface; a rotary motion in the opposite sense - counter clockwise or clockwise - causes the supporting element to move backward inside of said hollow cylindrical element with a progressive rolling of said layer of material, and therefore the compression of said radial surface.