Multilayer structures including a porous layer (370) and a non-porous layer (360) are useful as buttresses when associated with a surgical stapling apparatus. When the stapling apparatus (10) is fired it forces at least one staple to pass through openings in the staple cartridge (104), at least one multilayer buttress (350), the tissue, and openings in the staple anvil (204) to seal the tissue. Once stapled in place the porous layer (370) advantageously reduces bleeding, assists in sealing the wound and allows tissue ingrowth, if desired, while the non-porous layer (360) provides support for the porous layer and may assist in preventing the formation of adhesions.
