Several recent studies document a long-term beneficial effect of breast-feeding on later neurodevelopmental outcomes. The mechanisms involved are still unclear, but evidence is accruing that the fatty acid composition of human milk might play a role. In infants the composition of body fatty acids, from circulating erythrocyte lipids to brain phospholipids, is linked to the early diet (Farquharson et al. 1992; Makrides et al. 1994), and which fatty acids predominate among circulating lipids affects visual and neurodevelopmental performance test scores (Agostoni et al. 1995a, Makrides et al. 1995). These studies revealed that formula-fed infants showed low accretion of tissue long-chain polyunsaturated fatty acids (LC-PUFA) and lower visual and neurodevelopmental test scores than breast-fed infants.