An improved surgical fastener applying apparatus includes a cartridge half-section and an anvil half-section with the cartridge and anvil half-sections being relatively movable from an unclamped position to a fully clamped position. The apparatus includes a replaceable staple cartridge assembly having a plurality of surgical staples and a pivotably mounted safety lock-out. The safety lock-out is pivotable between an initial position in which a relative movement of the cartridge and anvil half-sections to the fully clamped position is permitted and a blocking position in which a relative movement of the cartridge and anvil half-sections to return them to their fully clamped position after the plurality of staples have been at least partially fired is prevented. The apparatus further includes a pivotably mounted firing lever for moving a pair of camming surfaces longitudinally. In addition, each of the presently disclosed cartridge and anvil half-sections of the fastener applying apparatus includes a clamping lever, which clamping levers are configured and adapted to enable the applying apparatus to be opened by either one of the cartridge half-section and the anvil half-section.