 This is an open, comparative, randomized 1:1, multicenter, European France, Germany, Czech Republic, Slovakia and Bulgaria, Phase 2B study on parallel groups of patients presenting with metastatic prostate cancer stage D2 or Tx Nx M1 M1a, with a PSA level 5-fold higher than normal that is PSA 20 ngmL, as quantitated by the Hybritech radioimmunoassay which return to normal within 6 months after the initiation of total androgen blockade therapy with leuprorelin 3.75 mg SR and flutamide. It will involve 314 preselected patients. 