The electro-encephalographic (EEG) characteristics and psychometric performance of 'normal' black South African peri-urban children were assessed in the course of a large-scale normative study. Children identified as being poorly nourished according to growth standards were compared with a group of mildly growth-retarded children and with another group with normal growth. The socio-economic backgrounds of the three groups were checked and found to be the same. The children had had access to regular clinic attendance and none had ever been hospitalised for any serious illness--in particular malnutrition. Across the entire age range the poorly nourished children invariably were found to fare worse on both EEG and psychometric measures than the normal group.