Planning options to mitigate losses due to coastal erosion in the coastal NSW, Australia were analysed using cost-benefit analysis. In all instances, the cost and benefits of policies and projects must be carefully weighed using a common monetary measuring rod. Yet, many different categories of benefits and cost must be evaluated, such as health impacts, property damage, ecosystem losses and other welfare effects. Furthermore, many of these benefits or damages occur over the long term, sometimes over several generations, or are irreversible (e.g. global warming, biodiversity losses). How can we evaluate these elements and give them a monetary value? How should we take into account impacts on future generations and of irreversible losses? How to deal with equity and sustainability issues?