Intensive investigation during the past 2 decades has led to an improved knowledge of the biology of the androgen receptor and a better understanding of how to assess for disease progression and the apparent existence of castrate-resistant prostate cancer. The result has been the clinical development of a new generation of hormonal therapy agents for achieving the androgen deprivation necessary to achieve castrate levels of circulating testosterone. It has also resulted in the realization that it is probably time to move away from using terms such as "hormone-refractory" and "androgen-independent" prostate cancer, given the clear evidence that significant, effective, ongoing suppression of testosterone, using better drugs and better assays, will continue to be the standard of care.