Modern gear boxes are characterized by high torque load demands@ low running noise@ and compact design. In order to fulfill these demands@ profile and lead modifications are being applied more and more. The main reason for the application of profile and or lead modification is to compensate for the deformation of the teeth due to load@ thus ensuring proper meshing of the teeth which will result in optimized tooth contact pattern. This paper will focus on how to produce profile and lead modifications by using the two most common grinding processes@ threaded wheel and profile grinding. In addition@ more difficult modifications@ such as defined flank twist or topological flank corrections@ will also be described in this paper.