Cyproterone (cyproterone acetate) is a steroidal antiandrogenic agent that inhibits the action of adrenal and testicular androgens on prostatic cells. Additionally, its progestogenic activity causes a centrally mediated reduction in testicular secretion of androgens. Studies have demonstrated the effectiveness of cyproterone monotherapy in patients with prostate cancer, and for those in whom orchiectomy is not an acceptable option cyproterone may be a useful alternative. In addition, the drug may be administered in combination with surgical or gonadotrophin-releasing hormone (GnRH) agonist-mediated castration to ensure ablation of adrenal androgens. However, the effectiveness of cyproterone in combination with these forms of testicular androgen deprivation remains to be fully established. Trials to date have not demonstrated prolonged survival in patients receiving the combination therapy. Importantly, however, cyproterone does prevent acute exacerbation of disease during initial treatment with a GnRH agonist. Furthermore, combination therapy tends to be associated with a lower incidence of hot flushes than GnRH agonist-mediated or surgical castration alone. Thus, cyproterone 200 mg/day has proven efficacy in preventing acute flare of disease and reducing the incidence of hot flushes associated with GnRH agonist therapy or orchiectomy. It may also facilitate maximal androgen deprivation in patients receiving GnRH agonist therapy. If this drug is used as monotherapy, dosages of 250 mg/day or greater will probably be required.