Enuresis nocturna is regularly treated by desmopressin, a vasopressin analog. Its side effects, notably neurological, are fortunately rare. We comment on 5 enuretic children on desmopressin who suffered from hyponatremic encephalopathy (natremia 115-127, median 117 mmol/l). RESULTS: Side effects appeared at therapeutic doses (10-40 mg/d intranasal). An excessive fluid intake at night was often noted, leading to a dilutional hyponatremia. This may be due to a lack of correct information to the parents. These children presented after a period of warning symptoms, such as headache, vomiting and altered consciousness. Parents could have sought earlier medical attention if they had been informed about these symptoms. CONCLUSION: In the absence of fluid restriction, severe hyponatremia can occur in enuretic children on desmopressin. It is therefore mandatory for the prescribing doctor to adequately inform patients and parents to limit fluids at night when desmopressin is used, and seek medical help quickly if any sign of intracranial hypertension appears.