Balancing of rotors is an indispensable process for the quality management, involving many stages from design to commissioning. With every further development of rotors - with new concepts, materials and machining methods - the demands on balancing technology change. In the search for the optimum solution to these complex tasks, no patent remedies will help, but only a sound knowledge of the theoretical background of balancing, its practical implementation and the performance of the various balancing systems.