A chipper knife adapted to be mounted in chippers which have a rotatable tool, in the form of a disc, drum or frustoconical member, on which a plurality of chipper knives are mounted has at least one cutting edge which is defined between two edge-forming surface portions of the knife at an acute angle to each other. At least one of the two edge-forming surface portions extends from the cutting edge inwardly to a shoulder extending parallel to and facing away from the cutting edge and defining a step surface on the knife behind the shoulder with respect to the rest of the adjacent knife surface and chipper knife.