This paper advocates the value of simulation to promote changes in kidney allocation. Due to the scarcity of organs and to the competition between transplantation centers to obtain the best organs for their patients, any change in organ allocation policy remains a sensitive issue in public health decision-making. Organ allocation is not easily available for prospective experimental study. Observational stud-ies only support limited changes. A simulation tool in this context permits the comparison of observed results against simulated ones. In our experience in France, it has shown to be a helpful tool during the allocation design phase providing objective facts for the debates and increasing the potential for change.