A stent graft (10) has a tubular body (12) of a biocompatible material and at least one fenestration (18, 20). The or each fenestration has a tubular side branch stitched into it with a portion of the tubular side branch extending within the tubular body and a portion of the tubular side branch extending exteriorly of the tubular body. The stitching by which the tubular side branch is mounted into the fenestration extends circumferentially and diagonally from one end of the tubular side branch to the other such that the tubular side branch extends from the tubular body at an angle thereto. The tubular side branch has a resilient ring around at least one and preferably both ends thereof and a self expanding stent in between them. The tubular side branch can have a circumferential linear portion (46) at an inner end to engage against the inner wall (58) of the tubular body. The tubular side branch can have a stent made from a single wire forming a first ring (45), a second ring (47), the second ring defining a plane which is substantially parallel to and spaced axially apart from the plane of the first ring and a number of helical wire portions (49) extending between the first and second ring. Preferably the wire is a shape memory wire such as Nitinol™ wire.