Thirty patients with advanced prostatic cancers (8 stage C, and 22 stage D) were treated for at least three months with D Trp6 LH-RH, a powerful LH-RH agonist. In all the cases in which the testosterone levels had been normal before treatment, the treatment led to a decline to the levels observed after castration. In seven cases, the drop was preceded by a rise in the first few days of treatment. Twenty two patients reacted favorably to the "medical castration" resulting from LH-RH agonists (11 improved and 11 remained stable). The improvements were mainly noted in patients who had not undergone previous treatment. Four deaths were registered in patients already at an advanced stage. Two of these patients presented with visceral metastases in circumstances such that a sudden deterioration due to the agonists cannot be excluded.