We investigated 53 adult ADHD-patients which visited our out patient clinic for first ADHD-diagnosis (17 females, 36 males; range of age: 18-56 years) for the frequency of a comorbid Asperger-Syndrome. Diagnosis of this autism-spectrum disorder was confirmed by applying the appropriate DSM-IV-criteria. Additionally we tested the power of the two screening-instruments "Autism-spectrum quotient" (AQ) and "Empathy quotient" (EQ) by Baron-Cohen for screening Asperger-Syndrome in adult ADHD.