A surgical stapling apparatus (10) comprising a housing, handle (24), elongated body (14), advancement assembly, and retraction mechanism (58) is provided. The movable handle is supported by the hosing, the movable handle being movable through an actuation stroke. The elongated body extends distally from the housing and defines a longitudinal axis, the elongated body having a distal end adapted to releasably engage a disposable loading unit. The advancement assembly includes an actuation shaft (46) and a driving pawl (42), the actuation shaft having a toothed rack (48) and being supported at least in part within the housing, the driving pawl being operatively associated with the movable handle and biased into engagement with the rack, wherein during the actuation stroke, the driving pawl is movable to effect longitudinal advancement of the actuation shaft. The retraction mechanism includes a release plate (64) operatively associated with the actuation shaft, the release plate being movable relative to the actuation shaft into operative engagement with the driving pawl to disengage the driving pawl from the rack.