Using the pooled data of recent demographic and health surveys of 20 countries in sub-Saharan Africa, the anthropometric measures collected on under-five year old children indicate that more boys rarely reach their growth potential compared to girls. In 9 countries, this difference is significant and, in the others, except Congo, malnutrition prevalence remains higher in boys, although not significant. This demonstrates that the explanation of child stunting in sub-Saharan Africa should systematically include the sex of the child. Hygiene and the diarrhoea negatively affect growth. Small morphology at birth is more discriminating between sex and has been seen to induce subsequent stunting.