Diarrhoea with dehydration in infants and young children still accounts for great morbidity and mortality in developing countries. Many attempts to control this major health problem have involved improved environmental sanitation, the provision of wholesome drinkable water and, more recently, the early oral replacement of fluid and electrolytes in affected children. This paper describes a study in which 75 infants and children attending busy outpatient departments of two hospitals were successfully rehydrated by oral fluid and electrolyte replacement using standard WHO-UNICEF packets. It highlights some of the advantages of this method and draws attention to one possible disadvantage, namely hypernatraemia. This complication could be avoided by concomitant administration of salt-free water or continuation of breastfeeding in young infants.