A stent graft (20) includes a stent graft for placement in a body vessel, the body vessel having a measured diameter at the level of side branches of the vessel and the side branches being located circumferentially on an inner wall of the vessel by a measured distances from a vessel datum point, the stent graft including:
a tubular body (20) of a biocompatible graft material and at least two fenestrations (54, 56) in the tubular body, the tubular body having a diameter of between 10 to 20% greater than the measured diameter of the branch vessel in the region of the fenestrations (54, 56), the fenestrations being spaced circumferentially around the tubular body from a selected graft datum point (41) by the measured distance, whereby when the stent graft (20) is introduced in to the vessel the fenestrations (54, 56) can be aligned with the side branches.