Cost-effective, sustainable strategies are urgently required to curb the global obesity epidemic. To date, fiscal policies such as taxes and subsidies have been driven largely by imperatives to raise revenue or increase supply, rather than to change population behaviours. This paper reviews the economic evaluation literature around the use of fiscal policies to prevent obesity. The cost-effectiveness literature is limited, and more robust economic evaluation studies are required. However, uncertainty and gaps in the effectiveness evidence base need to be addressed first: more studies are needed that collect ‘real-world’ empirical data, and larger studies with more robust designs and longer follow-up timeframes are required. Reliability of cross-price elasticity data needs to be investigated, and greater consideration given to moderators of intervention effects and the sustainability of outcomes. Economic evaluations should adopt a societal perspective, incorporate a broader spectrum of economic costs and consider other factors likely to affect the implementation of fiscal measures. The paucity of recent cost-effectiveness studies means that definitive conclusions about the value for money of fiscal policies for obesity prevention cannot yet be drawn. However, as in other public health areas such as alcohol and tobacco, early indications are that population-level fiscal policies are likely to be potentially effective and cost-saving.