A stent assembly comprises a stent and a side branch flap. The stent has a substantially tubular body which defines a primary lumen and is comprised of a plurality of interconnected stent members. Adjacent stent members define a plurality of stent openings that extend through the body and which are in fluid communication with the primary lumen. At least one stent opening is a side branch opening. The side branch flap is a non-tubular body having a planar structure. A first region of the planar structure is overlappingly positioned across a portion of the side branch opening prior to deployment. A second region of the planar structure is engaged to a portion of the body of the stent immediately adjacent to the perimeter of the side branch opening. When the assembly is deployed the first region of the flap is displaced radially outward from the side branch opening.