A double-blind crossover study of the alpha-blocker Nicergoline was carried out in sixteen patients affected by benign prostatic bladder outflow obstruction. The "irritative" symptoms of prostatic hypertrophy, including nocturnal frequency and dysuria, were improved after Nicergoline significantly more than after placebo. In 10 further patients with prostatic hypertrophy, peak and mean flow rates increased by 50% and 77% respectively after the acute administration of Nicergoline. No side effects were detected. In conclusion Nicergoline seems to be active and well tolerated in the treatment of benign prostatic obstruction.