The implications of ADHD for sexual delinquent behavior were investigated in a sample of 127 male sexual delinquents for whom social, forensic and psychiatric data were collected. For the retrospective evaluation of ADHD-symptoms, we used the Wender Utah Rating Scale (WURS, 61-item version). We also used the Eysenck Impulsiveness Questionnaire for the assessment of impulsivity. The prevalence of ADHD within the group of sexual delinquents was 27.6 % with a persistence rate of 14.2 % at a cut-off point of 90 in the WURS. The prevalence of ADHD within the control group was 7.8 % with a persistence rate of 3.0 %. The prevalence within the group of sexual delinquents dropped to 15.7 % for childhood ADHD-symptoms and 11.0 % for partial ADHD persistence in adulthood using a cut-off score of 100. In the control group the rates were 4.8 % and 2.4 % respectively. Based on ICD-10 criteria, 35.4 % of the sexual delinquents had no psychiatric disorder. We found personality disorders of the antisocial type (22.1 % of the sample) and paraphilias in 25.2 %. Approximately, half of the delinquents with paraphilia met the criteria of pedophilia. We also found schizophrenia, organic psychiatric disorders and mental retardations in less than 5 %. The criminal careers of the sexual delinquent group with a history of childhood ADHD symptoms started 10 years earlier. We also found a significant correlation between previous convictions and the retrospective diagnosis of ADHD symptoms. This was more prominent when a previous sexual offence could be found in their criminal record. These results illustrate the hypothesis, that in addition to paraphilias the presence of ADHD-symptoms might be an important vulnerability factor for sexual delinquency, esp. when there is a persistence into adulthood. This demonstrates the need for an early therapeutical intervention, since 44.1 % of the sample had previously undergone psychiatric treatment.