A disposable linear surgical stapling instrument comprising a body with handle means and trigger means and, at its forward end, a fixed anvil-supporting jaw. A movable jaw comprising a staple cartridge is mounted on the body and is operatively connected to the handle means and trigger means. An adjustment bolt is slidably mounted in the body and is shiftable forwardly and rearwardly therein by an adjustment knob rotatively mounted at the rearward end of the body. The adjustment bolt, when shifted forwardly, shifts the handle means and trigger means forwardly and the movable jaw toward the fixed jaw, the staple cartridge approaching the anvil. A staple driver is connected to and shiftable by the trigger means to drive staples from the cartridge, through the tissue to be sutured and against the anvil over a range of distances between the anvil and the cartridge constituting the working gap of the instrument. The adjustment bolt also actuates indicator means to each side of the instrument indicating when the working gap has been achieved. An alignment pin is mounted on the body, extending through the cartridge, and is shiftable to an operative position extending into the fixed jaw. Safety means prevents rotation of the adjustment knob unless the alignment pin is in its operative position. Another safety means prevents actuation of the trigger means until the distance between the anvil and cartridge approaches the working gap. Additional means locks the trigger means after achieving its actuated position to give visual, tactile and audible indication that the staples have been formed and implanted.