The authors analyzed 52 forensic-psychiatric reports of child molesters. They classified paedophilia according to the diagnostic criteria of the ICD-10 and DSM-IV as well as a modified version of these criteria introduced by Beier and themselves. 48% of the paedophils had different socio-demographic characteristics from the general population of paedophils and 76% had psychiatric co-morbidity. There is no psychiatric diagnostic system and classification approved and fully validated in literature. The results support the view that the existing typologies of dissexual behaviour have limited validity. Among the paedophilic sex offenders 76% had psychiatric comorbidity.