PROBLEM TO BE SOLVED: To provide a surgical stapling apparatus configured for use with disposable loading units.SOLUTION: In various embodiments, the surgical stapling apparatus includes a retraction system interfacing with an operation shaft movably supported within a handle housing. The operation shaft is configured to move axially within the handle housing from a fully retracted position to a fully fired position in response to operation of a movable handle operably mounted to the handle housing. The retraction system serves to automatically retract the operation shaft to the fully retracted position when the operation shaft has moved to the fully fired position.COPYRIGHT: (C)2009,JPO&INPIT