An anvil and driver assembly for a surgical skin stapling instrument producing formed and implanted skin staples of more consistant and perfect configuration. The anvil provides an anvil surface which supports the crown of the staple during the forming operation. The driver has an inverted U-shaped notch formed therein which defines parallel side edges to bend the staple legs about the anvil and a transverse edge joining the side edges and adapted to contact the crown of the staple near the end of the forming operation. In the anvil and driver assembly of the present invention, the clearance between the parallel bending edges of the driver and the adjacent anvil edges is greater than the transverse dimension of the staple wire. The anvil surface of the anvil is concave and the crown contacting edge of the driver is so configured as to impart a temporary bow in the staple crown near the bottom of the driver stroke, which bow is of such dimension as to preclude plastic deformation of the crown. This produces a more generous bend and a slight over-bend at the junctures of the staple legs and the crown such that when the crown is released by the driver and returns to its rectilinear state, this action of the crown will compensate for the natural spring-back properties of the material from which the staple is made at the above noted junctures, consistantly producing the desired final formed configuration of the staple.