Hypernatremic dehydration is a serious condition in the newborn period. We present 5 infants with hypernatremic dehydration due to breastfeeding; one of them died because of brain edema during treatment.Hypernatremic dehydration in breast-fed newborns is secondary to insufficient lactation and all mothers should be encouraged about breastfeeding, taught the signs of successful breastfeeding, and the warning signs of dehydration. Here, we discuss hypernatremic dehydration in breastfeeding neonates, its causes and treatment.