This paper summarizes some of the literature on the cost effectiveness and cost benefit of food fortification with selected micronutrients most relevant for developing countries. Micronutrients covered include iron, iodine, vitamin A, and zinc. The main focus is on commercial fortification, although home fortification and biofortification are mentioned. Fortification with iron, vitamin A, and zinc averts significant numbers of infant and child deaths and is a very attractive preventive health-care intervention. Fortification with iron, iodine, and potentially zinc provides significant economic benefits and the low unit cost of food fortification ensures large benefit:cost ratios, with effects via cognition being very important for iron and iodine. Fortification will not reach all individuals and is most attractive as an investment where there is a convenient food vehicle, where processing is more centralized, and where either the deficiency is widespread or the adverse effects are very costly even though only a small group is affected.