Abstract With the increasing complexity of modern manufacturing and assembly processes, the number of alternatives to be analyzed during the planning process has also grown. To help planning staff to quickly analyze solution alternatives, different computer aided planning tools have been developed. However, they do have the disadvantage that their capacity for illustration extends only to specific branches of manufacturing systems. Apart from this initial starting position, as described above, this serves as the basis for the development of the simulation program GISA (Graphic Interactive Simulation and Animation) at the Laboratory for Machine Tools and Production Engineering (WZL) at the University of Technology, Aachen, Federal Republic of Germany. Using the GISA simulation program, the user can quickly and effectively describe the various facets of manufacturing systems without extensive foreknowledge of EDP technology. In order to assist the operator, the program system GISA operates on the basis of a graphical interactive dialogue between computer and user. The structure of these planning tools is described and illustrated with an example from an industrial application.