Abstract: A fuel injection nozzle includes a body in which is formed a blind bore. An outlet orifice communicates with the blind end of the bore and adjacent the blind end of the bore is a seating which in use is engageable by a valve member. The body is formed from hardenable material and the nozzle body is formed in such a way that the seating surface has a high hardness value, the hardness value of the material diminishing to the exterior surface of the body. This is achieved by machining the exterior surface to remove a hardened layer or a hardenable layer produced during a carburizing operation.