Common sense always links good nutrition with optimal development of infants and, particularly, of brain development. Fortunately, brain development is rather resistant to nutritional deficiencies, provided that the psychomotor stimulation of the baby is adequate, as shown by many authors in the case of global protein energy malnutrition. For two types of micronutrient deficiency, those of iron and long-chain polyunsaturated fatty acids, it is easier to isolate the role of micronutrient deficiency from the role of psychosocial deprivation, although not entirely. Term babies seem to be perfectly able to synthesize both docosahexaenoic acid (DHA) of the n-3 series and arachidonic acid (AA) of the n-6 series in sufficient quantities for their normal brain development, provided that their diet contains the precursors of the two series in adequate proportions. For low-birth-weight infants, AA does not seems to be necessary, and the discussion is still open regarding the essentiality of DHA. For iron, it seems that the level of education of the mother affects both the iron status of the child and its psychomotor development. The additional role of iron deficiency on infection sensitivity and muscular strength could also have an effect on the overall nutritional status and on the ability to communicate with the environment and learn.