More than 250,000 patients with nocturnal enuresis have been treated with DDAVP in the United States since 1989. It adequately controls nocturnal enuresis in over half of patients with significant improvement in their quality of life. Although the overall incidence of adverse effects associated with treatment of nocturnal enuresis with DDAVP is low, it is not a benign drug particularly when used in patients at extreme of age. A review of the literature and the present case demonstrate that the potential risk factors for hyponatremia following administration of DDAVP include hepatic disease, surgery, stress, pain, renal disorder, excessive fluid intake, and increased dose of DDAVP. Potentially serious side effects of DDAVP administration such as hyponatremia and seizure may be prevented by close monitoring of serum electrolytes, urine output, as well as fluid restriction and avoidance of solutions with low-sodium content.