A collapsible stent graft for aortic aneurysms includes a collapsible inner tubular member (26) and an outer layer (24) fused or adhered thereto such as to provide a spiral inflatable member (22) therebetween. The stent graft is inserted into an artery in the collapsed state and then expanded into position by introducing a liquid into the inflatable member and sealing the member. The graft is held in place by an expandable stent (40).