The present disclosure relates to surgical fastener applying apparatus for sequentially applying a plurality of surgical fasteners to body tissue. The surgical fastener applying apparatus includes a replaceable cartridge assembly receivable in a distal end portion of a cartridge receiving half-section, the cartridge assembly including a safety lockout pivotably disposed along the upper surface of the cartridge assembly and movable from an unlocked orientation permitting assembly of an anvil half-section to the cartridge receiving half-section, to a locked orientation preventing assembly of the anvil half-section to the cartridge receiving-half section.