A vascular prosthesis for a blood vessel of a patient, which has the following: a hollow-cylindrical main body with a longitudinal axis, a proximal opening and a distal opening, and also a main lumen extending between the proximal opening and the distal opening, the main body having a proximal end region and a distal end region, which respectively comprise the proximal opening or the distal opening, and also an intermediate region arranged between the proximal end region and the distal end region, a plurality of stent rings, which are not connected to one another, which are arranged spaced apart one behind the other in the longitudinal direction of the vascular prosthesis and running around in a meandering formation, the stent rings respectively having ogives and webs connecting them, a prosthesis material, to which the stent rings are attached, at least four side branches (22, 23, 24, 25), which extend distally into the main lumen from fenestrations in the prosthesis material lying between the stent rings, wherein each side branch (22, 23, 24, 25) has a first side-branch opening and a second side-branch opening and also a side-branch lumen extending between the first side-branch opening and the second side-branch opening, the first side-branch opening respectively being firmly attached to the prosthesis material, respectively, via a fenestration, such, that a side-branch attachment is formed; characterized in that the vascular prosthesis has four side branches (22, 23, 24, 25), which extend into the main lumen, and are arranged in the intermediate region, the intermediate region having a smaller diameter d2 in comparison with the diameters d1, d3 of the end regions (15, 17). a hollow-cylindrical main body with a longitudinal axis, a proximal opening and a distal opening, and also a main lumen extending between the proximal opening and the distal opening, the main body having a proximal end region and a distal end region, which respectively comprise the proximal opening or the distal opening, and also an intermediate region arranged between the proximal end region and the distal end region, a plurality of stent rings, which are not connected to one another, which are arranged spaced apart one behind the other in the longitudinal direction of the vascular prosthesis and running around in a meandering formation, the stent rings respectively having ogives and webs connecting them, a prosthesis material, to which the stent rings are attached, at least four side branches (22, 23, 24, 25), which extend distally into the main lumen from fenestrations in the prosthesis material lying between the stent rings, wherein each side branch (22, 23, 24, 25) has a first side-branch opening and a second side-branch opening and also a side-branch lumen extending between the first side-branch opening and the second side-branch opening, the first side-branch opening respectively being firmly attached to the prosthesis material, respectively, via a fenestration, such, that a side-branch attachment is formed; characterized in that the vascular prosthesis has four side branches (22, 23, 24, 25), which extend into the main lumen, and are arranged in the intermediate region, the intermediate region having a smaller diameter d2 in comparison with the diameters d1, d3 of the end regions (15, 17).