The national food surveys of 1974, 1979 and 1989 were analysed in order to evaluate the levels and tendencies of the malnutrition prevalence in children one to five years old. The malnutrition prevalence maintained its level with minor changes: it increased from 49 to 53 per cent in the group with -1 SD, and from 17 to 19 per cent in those with -2 SD, in relation with the WHO [correction of OMS]-NCHS standards. If the information is analysed by social sectors, it is possible to conclude that the apparent stability is due to a process of nutritional polarization: the areas that had lower figures improved as the poor and Indian areas with high prevalence of initial malnutrition deteriorated even more.