Iontophoretic delivery of desmopressin acetate (DDAVP) was assessed for delivery efficiency and drug stability, both in vitro and in vivo. The effect of current intensity and duration of current application on the decomposition of DDAVP was investigated in vitro. It was shown that when a current of 0.1 mA was applied for 5 min, the decomposition of DDAVP was negligible. In vivo experiments under the same conditions showed that the antidiuretic response to DDAVP persisted for about 6 h. Furthermore, when this iontophoresis was repeated 3 times at intervals of 4 h, the antidiuretic response persisted for about 11 h. These results suggest that repeated short-termiontophoresis is a safe and effective technique for transdermal delivery of DDAVP.