We report the case of a patient with an idiopathic syndrome of inappropriate secretion of ADH for more than 6 years. Water restriction was effective only during hospital care but was socially difficult to maintain at home, so that the patient presented frequent symptoms of water intoxication. Normal natremia was also obtained with a high salt intake (9 g/day) but this induced leg edema mild dyspnea and gastric intolerance. The patient was however successfully treated for more than 5 years without any side effects with oral urea (30 g/day) allowing her a normal fluid intake (1-1.5 liters/day). Oral urea, even during long periods, is a safe and effective therapeutic approach for patients with chronic SIADH which is not controlled by water restriction alone.