Despite the well-known advantages of breast-feeding to both mother and infant, malnutrition of breastfed infants does occur. We report two term neonates who presented in the 3rd week of life with severe wasting, hypernatraemic dehydration and pre-renal failure while being exclusively breastfed. Breast-milk sodium levels were markedly elevated on admission. Both infants recovered following adequate hydration and showed excellent catch-up growth during follow-up while exclusive breast-feeding was maintained. The critical malnutrition in both cases was detected by the family physician during routine postnatal visits. Both mothers were well motivated toward breast-feeding and were unaware of the severity of the baby's illness.