Acute hyponatremia is a state of emergency with high morbidity and mortality. Severe hyponatremia is accompanied by a particular brain edema. As a child, with hyponatremia normally encountered while dehydrated during heavier gastroenteritis. Hyponatremia may also be caused due to oral intake more free water or hypotonic fluids. The authors present two cases of infants (aged 15 months and 12, respectively), which was accompanied by severe hyponatremia (118.2 mmol/L and 120.2, respectively) impaired consciousness, in one of the cases have required temporary artificial ventilation. Cause of severe hyponatremia in both infants was excessive intake of fluids, especially sweetened, which were administered to children for their soothing. For this condition is used term a€žcompulsive water drinkinga€œ or a€žnormal children who just like to drink a lota€œ. Parents of children and pediatricians should be informed of the possibility of water intoxication in an uncontrolled water intake well informed.