The treatment of metastatic castrate-resistant prostate cancer (mCRPC) has evolved rapidly with the recent approval of a number of treatments and agents, including docetaxel, sipuleucel T, abiraterone, cabazitaxel, and enzalutamide. Enzalutamide (previously MDV-3100) is a novel oral androgen receptor inhibitor that targets multiple steps in the androgen receptor signaling pathway. The randomized phase III AFFIRM study demonstrated significant improvements in a number of efficacy endpoints, including the primary endpoint of overall survival and secondary endpoints of progression-free survival, and time to prostate-specific antigen progression in patients with progressive mCRPC who had received prior treatment with docetaxel. Enzalutamide was well tolerated and there were comparable incidences of grade 3 or greater adverse events reported for the enzalutamide and placebo control arms in AFFIRM. Unlike some other treatments for mCRPC, enzalutamide does not require administration with steroids. The ongoing randomized phase III PREVAIL trial will investigate the efficacy and safety of enzalutamide in chemotherapy-naïve patients with mCRPC. Additional trials are investigating the use of enzalutamide in a number of disease settings.