A rotating cutting tool to cut asymmetrical teeth in a gearwheel in which each tooth (21) has an active flank (A) with a convex profile meshing with the profile of a tooth of an opposing gearwheel meshing with the gearwheel and a secondary concave flank (S), provided with teeth (11) on a generally helical path which extends from one side to the other with respect to a median cross-section (M-M) of the tool which is intended to be intersected by the radius Rp of the gearwheel which is at right angles to the axis of rotation of the tool working on the gearwheel to cut its teeth. The helical teeth have a first flank (CA) which is intended to cut the said active flank (A) of the gearwheel teeth and a second flank (CS) intended to cut the secondary flank (S), the pitch (P1) between the first flank (CA) of the helical teeth being constant and the pitch (P2) of the second flank of the teeth being smaller than the pitch (P1).