The study will include patients with localized prostate cancer who experience erectile
dysfunction following bilateral nerve-sparing radical prostatectomy. Patients will be
randomly assigned to three treatment arms: Tadalafil 5 mg once a day, Tadalafil 20 mg on
demand (prior to anticipated sexual activity), and placebo. Patients will stay on therapy for
9 months and after withdrawal of medication for 6 weeks, patients will be evaluated for
recovery of unassisted erectile function (without medication). An open-label extension for
three months will evaluate the responsiveness of all patients to Tadalafil 5 mg once a day.
Further objectives are to evaluate the treatment satisfaction of the respective therapies.