A side branch stent graft (1) suitable for the iliac arteries has a main tubular body (3) of a biocompatible graft material and a tubular side branch (5). The tubular side branch is affixed into the main tubular body so that a side branch lumen is in fluid communication with a main lumen. There is at least one external zig-zag stent (13) on the main tubular body proximal of the tubular side branch, one central external stent (14) which also encompasses the side arm, at least one external zig-zag stent (16) on the main tubular body distal of the tubular side branch and one internal zig-zag stent (15) at the distal end of the main tubular body. A reinforcing ring (9) is around the proximal end of the main tubular body and stitched thereto.
