A surgical stapling instrument (10) comprises a staple cartridge assembly (22) having a plurality of rows (37) of staple receiving slots (36), an anvil assembly (30) having an anvil member (26) defining a plurality of rows of staple forming recesses (27), the staple cartridge assembly, the anvil assembly, or both, having one or more attachment members (132)； and a staple line reinforcement material (50) attached to the attachment members by ultrasonic welding. The staple line reinforcement material can be attached to an anvil assembly utilizing a retainer (60).
