This is a Phase1/2, open-label, uncontrolled study, involving Dose-Escalation Cohorts, where dose will be escalated to next dose with the safety, tolerability, and PK being evaluated in metastatic castration-resistant prostate cancer (mCRPC) patients and an Expansion Cohort, where the efficacy, safety, and PK of MDV3100 in post-chemo mCRPC patients will be evaluated. After evaluation of the safety and tolerability in Dose-Escalation Cohorts, additional patients are included in Expansion Cohort.