Today surgical education and training do not offer a realistic scenario to the medical students. Practical skills are mostly acquired by operating cadavers which offer material properties and physical behaviour different from living humans. Simulation systems can be used in this area to improve medical education and to offer a more authentic scenario to the future surgeons. Besides the field of training and education, surgical simulators can also be used for pre-operative planning. A big need for simulation can be determined for surgery in complex regions of the human body, such as the cranio-facial or the cardiac area. It is very important that no vital structures of the body are damaged during surgery which can be achieved by the use of an appropriate simulation system. The main focus of this paper is the description of our approach for a risk reducing surgery simulation concept for use in pre-operative planning and medical training. We will introduce the existing system for simulation of surgical tasks in the cranio-facial and cardiac area. This system is based on volumetric models which can be manipulated using the Finite-Element-Method. Furthermore we will show how this system is modified and extended to suffice the requirements of risk reducing surgery. The determination and modelling of the risk regions will be explained and the system reaction will be illustrated. Finally we present some results of the existing simulation system and first outcome of our approach risk reducing surgery.