There is some evidence that hormonal and serotonergic alterations may play a role in the pathophysiology of paraphilias. The aims of the present study were to examine: 1) baseline plasma cortisol, plasma prolactin, and body temperature; and 2) cortisol, prolactin, body temperature, as well as behavioral responses to metachlorophenylpiperazine (mCPP) The sexual abuse of children (pedophilia) represents a significant proportion of about 25% of all sexual offences (Moller and Bier-Weiss 1995). Between 100,000 and 500,000 children in the United States are thought to be sexually molested annually (Fuller 1989). Pedophilia is one of the sexual deviation disorders or paraphilias, which are diagnosable psychiatric syndromes characterized by recurrent fantasies about deviant sex, intense associated cravings, and stereotypic behavioral responses (Berlin and Meinecke 1981). The DSM-IV (APA 1994) describes the paraphilias as an impulse control disorder (ICD) (Cosyns 1999). Indeed, patients with paraphilias experience tension or arousal before committing the sexual act, experience pleasure during the act and feel a release of tension after the act (Cosyns (Greenberg et al. 1996).Although there is a substantial evidence in the historical and anthropological record of pedophilia, there has been little research on the biological pathophysiology of pedophilia. Alterations in the metabolism of serotonin (5-HT) may play a role in the pathophysiology of paraphilias (Kafka 1997). 1) 5-HT is involved in male sexual behavior; 2) serotonergic agents, such as selective 5-HT reuptake inhibitors (SSRIs), can ameliorate paraphilic sexual behaviour (review: Balon 1998; Greenberg et al. 1996;Zonana and Norko 1999); and 3) there is an extensive number of clinical and animal studies supporting the hypothesis that a dysfunction of the 5-HT neurotransmitter system is an important factor in the underlying pathology of impulse control disorders (ICD) and aggression/violence (Linnoila et al. 1983;Markowitz and Coccaro 1995;Kavoussi et al. 1997;McElroy et al. 1995;Coccaro 1999).A number of studies report lower CSF 5-hydroxyindole-acetic acid (5-HIAA) in ICD and aggressive patients, such as impulsive offenders and fire setters (review: Virkkunen et al. 1989;Coccaro 1999). The prolactin responses induced by D-L-fenfluramine (an indirect 5-HT agonist which releases 5-HT) are significantly and inversely related with measurements of aggression (Coccaro et al. 1989;O'Keane et al. 1992). Several authors found inverse relationships between platelet 5-HT transporter binding and impulsivity/aggression (Simeon et al. 1992;Coccaro et al. 1996). Patients with episodic aggression show a significantly lower platelet [ 3 H]-5-HT uptake than controls (Brown et al. 1989). Coccaro et al. (1997) described a positive correlation between the number of platelet 5-HT2A receptor sites and measures of aggression, in personality-disordered patients. Tryptophan depletion in subjects with preexisting aggressive traits induces increased aggression (Cleare and Bond 1995). The ...