A surgical stapling apparatus comprising a handle assembly (12) including a moveable handle (24), the movable handle being movable through at least one actuation stroke an elongated body (14) extending distally from the handle assembly and defining a longitudinal axis, a tool assembly(17) mounted for articulation adjacent a distal end of the elongated body a flexible and longitudinally movable drive beam (266) to effect the ejection of surgical staples from the tool assembly, and an actuation shaft (46) mounted for longitudinal movement in response to manipulation of the movable handle, the actuation shaft being arranged to move the drive beam longitudinally.
