A surgical stapling apparatus is provided which includes a first jaw supporting an anvil assembly and a second jaw supporting a cartridge assembly. The cartridge assembly supports a firing lockout assembly which includes a latch member having a blocking member. The latch member is movable between a first position and a second position. In the first position, the blocking member of the latch member is aligned with the stop surface of the drive member to prevent advancement of the drive member within the tool assembly and in the second position, the blocking member is misaligned with the stop surface of the drive member to permit advancement of the drive member within the tool assembly. A biasing member is positioned to urge the latch member towards the first position. In the retracted position of the drive member, the latch member is in the first position.