We present a catheter related severe hypernatremia in a 2-month-old baby who was admitted to the pediatric intensive care. Imbalance of plasma sodium is commonly seen in pediatric intensive care patients. The water and sodium balance is a complex process. Especially, brain and kidneys are the most important organs that affect the water and sodium balance. Other mechanisms of the cellular structure include osmoreceptors, Na-K ATPase systems, and vasopressin. Hypernatremia is usually an iatrogenic condition in hospitalized patients due to mismanagement of water electrolyte imbalance. Central venous catheterization is frequently used in pediatric intensive care patients. Complications of central venous catheter placement still continue despite the usage of ultrasound guidance. Malposition of central venous catheter in the brain veins should be kept in mind as a rare cause of iatrogenic hypernatremia.