The androgen receptor remains the key player in patients with castration-resistant prostate cancer (CRPC). Available agents capable of blocking early adrenal androgen production have limited activity and can lead to significant toxicities. Abiraterone acetate, a pregnenolone analog, is a small molecule that irreversibly inhibits CYP17, a rate-limiting enzyme in androgen biosynthesis. Several clinical trials have demonstrated the safety and efficacy of this compound in men with metastatic CRPC. Recently, a randomized phase 3 trial evaluating abiraterone acetate in docetaxel-refractory CRPC patients demonstrated a survival improvement over placebo-treated patients (14.8 vs 10.9 months; HR 0.646; P < 0.0001). A similar trial in the pre-chemotherapy setting has completed accrual and is undergoing analysis. Here we review the rationale and clinical development of abiraterone acetate in men with CRPC.