Antiandrogens, substances that prevent androgens from expressing their activity at target cells, play an important role in the treatment of prostate cancer. The most frequently used substances have either a steroidal structure (cyproterone acetate) or a non-steroidal structure (Flutamide or Anandron). Antiandrogens have been tested both alone and in combination with treatments aimed at inhibiting testicular secretion (castration, LH-RH analogs), thereby producing complete blockade of androgen secretion and action. Patients treated by such combination protocols have often shown an improvement in the percentage of remissions and, less often, improvement in survival. Administration of antiandrogens improves the clinical symptoms of patients with benign prostatic hypertrophy, but the exact mechanism of their action requires further investigation. Cutaneous manifestations due to hyperandrogenicity (hirsutism, alopecia, acne) have also been improved by cyproterone acetate, which is often given together with estrogens (reversed sequential regime), by spironolactone or topically applied products. Finally, antiandrogens have been successfully used to treat breast cancer in men, early puberty, hypersexuality and sexual deviations.