A method for causing a permanent increase in the length and girth of a male subject's penis, the method comprising treatment comprising the step of (a) administering to the male an effective amount of a vasodilator selected from the group consisting of a vasodilator per se and compositions thereof comprising a pharmaceutically-acceptable diluent or carrier, to induce a cumulative prolonged engorgement of the subject's penis; and (b) repeating step (a) as necessary to cause the increase during the treatment. A potentiator which enhances the effect of the vasodilator may also be used.