The instant invention provides potent antiandrogen compounds, such as 3β-acetoxyandrost-1,5-diene-17-ethylene ketal and 3β-hydroxyandrost-1,5-diene-17-ethylene ketal, and methods for their use in the prevention and treatment of biological conditions mediated by androgen receptors. Thus, for example, compounds of the invention are useful in the prevention and treatment of prostrate cancer. Furthermore, it has been discovered that compounds of the invention are useful in the prevention and treatment of androgen-independent cancers such as androgen-independent prostrate cancer. Finally, inventive compounds may be used to treat antiandrogen induced withdrawal syndrome.