Animal experimentation has shown that early iron deficiency irreversibly affects brain iron content and distribution, resulting in neutransmitter and behavioural alterations. Even though extrapolation of animal data is often misleading, iron-deficiency anaemia has been consistently shown to be associated with psychomotor delays in infancy. The areas most involved are language and body balance. In these infants iron therapy, in most cases was not sufficient to reverse psychological effects even after complete correction of haematological measures. These findings may imply that the impact of iron-deficiency anaemia during infancy may be associated with irreversible adverse effects on cognitive performance. Careful follow-up studies of these infants at 5-6 years of age has shown that cognitive disadvantages persist, now assessed with a comprehensive set of psychological tests that reliably predict future competence. Thus, if once anaemia ensues, even timely and adequate iron therapy seems to be ineffective in reversing these behavioural and cognitive disadvantages; the only practical way to approach this problem is by prevention of iron deficiency in infancy. Health authorities, having been shown that treatment of iron deficiency anaemia is already too late to reverse potential deficits, should strive to prevent iron deficiency with adequate food fortification strategies or by supplementing targeted population groups.