459 trainees in Anesthesia and Intensive Care Medicine, accompanied by fully certified specialists from several Belgian University Hospital Centers, spend at least a 3 hour session at the Anaesthesia Simulator. Each session comprises three segments: the briefing, the simulation session and the debriefing. The use of simulations allows significant individualization of the learning experience. The simulator helps to develop the capacity to understand, explain a phenomenon and to resolve problems. Another important aspect of the use of the simulator involves the trainee's "right to make mistakes". This allows to widen the spectrum of executional situations, and decreases the number of dangerous situations. Two University Centers (ULg and UCL) have each organized simulator sessions despite some differences in their approaches. The simulator is a teaching tool worthy of an obligatory role in the most up-to-date training possible of modern anesthesiologist. This is all the more important given that the current practice of anesthesiology is so complex that any error could cost a human life.