Libido and male sexual behaviour are under the control of complex testosterone-dependent neuro-endocrine mechanisms. Better knowledge of these mechanisms has allowed to modulate sexual behaviour using drugs. Indeed, it is possible to block spontaneously uncontrollable sexual pulsions of aggressive hypersexual men by dropping testosterone secretion and consecutively decreasing androgen effects on target cells. From now, mutilating neurosurgery and treatment with either estrogens or antigonadotrophic progestagens are withdrawn. Cyproterone acetate, acting as a competitive inhibitor of testosterone action through its binding to androgen receptors, has been used with efficacy in 80% of cases studied. However, the therapeutic use of cyproterone acetate is limited by three drawbacks: i/potential side effects, ii/exclusive oral route of administration and iii/lack of available biological criteria as a control of the good observance of the treatment. We studied the efficacy of a GnRH analogue (Triptoreline), which induces a reversible hormonal castration and of which both the formulation and the route of administration avoid the inconveniences linked to a treatment with cyproterone acetate. 3.75 mg triptoreline injected intramuscularly once a month had been very effective on clinical and biological parameters in 5/6 aggressive hypersexual patients. In 3 of them a previous treatment with cyproterone acetate had been uneffective. Such a reversible hormonal castration suppressing sexual addiction, would lead to favourable conditions for psychotherapy.