A self-contained gas powered endoscopic surgical apparatus so is provided for placing lateral lines of surgical fasteners into body tissue. The apparatus includes a frame portion 52, an elongated portion 54 extending from the frame portion, and an articulating fastener applying assembly 58 associated with a distal end of the elongated portion. The fastener applying assembly includes a base portion, a staple cartridge housing, and an anvil member 56 which has a forming surface thereon against which surgical fasteners are driven as they are ejected from the cartridge housing. A self-contained pneumatic system 68 is associated with the frame portion and is actuable to eject the surgical fasteners from the cartridge assembly.; A first mechanism is provided for effectuating the rotation of the fastener applying assembly about an axis defined by the body portion, a second mechanism 452 is provided for effectuating the articulation of the fastener applying assembly, and a third mechanism 562 is provided for independently rotating the cartridge housing and anvil member relative to a longitudinal axis defined by the base position to increase the range of operability of the apparatus.