Allocation decisions in emergency medicine must occur when demand for emergency services exceeds supply. In many circumstances, strong clinical or cost evidence upon which to base allocation decisions is lacking. In these circumstances, patient or community preference may be used to inform decisions. If preference is to be incorporated into allocation decision-making, scientifically rigorous quantitative methods should be chosen for measuring preference. This article describes the theoretical background, advantages, risks and applications of discrete choice experiments for measuring patient preference in emergency medicine.