Desmopressin (DDAVP) is used to improve hemostasis in patients with bleeding disorders. The side effects of DDAVP in adults and children are benign. However, there has been concern regarding the development of hyponatremia and seizures after the use of DDAVP in young children. The authors describe three children under 3 years of age who developed hyponatremia (two also developed seizures) following intravenous administration of DDAVP at a standard dose of 0.3 mug/kg. Fluid restriction, avoidance of hypo-osmolar fluid, and close monitoring of fluid and electrolytes for 12 to 24 hours after the administration of DDAVP in children younger than 3 years of age is recommended.