Fe deficiency is considered to be the commonest of nutritional deficiencies worldwide. Adverse effects are stated to include lower growth rate and impaired cognitive scores in children and poor pregnancy outcome and lower working capacity in adults. In the present review, Fe intake, stores of the element, the magnitude of deficiencies and the benefits from interventions, as reflected in the results of clinical trials, are discussed. Because of inadequacies of knowledge in numerous respects, more information is needed regarding the extent to which clinical trials relate to public health realities, before introducing regional or national supplementation programmes. While Fe supplements are needed in certain groups, and in particular regions, increased dietary intakes could be supplied by food fortification, as well as by individual improvements in intake.