Proposals for special products in the Doha negotiations on agricultural tariffs seek to achieve vitally important goals of food security, livelihood security and rural development. They use an instrument—exceptions to tariff binding reductions on staple foods—that can only have an effect if it allows applied tariff rates on imported goods to be higher than their level in the absence of this exception, and if this causes prices for producers and/or consumers to be higher than they would otherwise be. A key concern with this approach is that staple foods are frequently important cost items to poor consumers, and the marketable surplus of producers in poor countries is frequently small or negative, resulting in small benefits (or even costs) to poor producers. Results using household data for four poor countries show that—if these flexibilities were used— the impacts of higher-than-otherwise staple food prices on poverty differ substantially by commodity and by country, but that poverty increases would be more frequent, and larger, than poverty reductions. The results highlight the need for caution in using the flexibility provided by this instrument and the need for other measures, such as improvements in technology, rural infrastructure and education, if poverty is to be successfully reduced.