Six men with severe paraphilia had been treated with depot gonadotrophin luteinizing releasing hormone analogue (GnRHa) (triptorelin 3.75 mg per month intramuscularly). In 5 cases, the treatment ended their deviant sexual behavior and markedly decreased their sexual fantasies and activities without further significant side effects than those related to hypoandrogenism. This clinical improvement was parallel to the gradual decrease of plasma testosterone level to castration values within the first month. The beneficial effect of this treatment had been maintained at follow-up varying from 7 months to 3 years. One patient interrupted the treatment at the end of the first year and relapsed within 10 weeks. GnRHa treatment, which leads to reversible castration, may constitute a promising treatment of paraphilic behavior and may favor the possibility of concurrent psychotherapy.