AIM: To establish the validity of a Danish version of the Attention Deficit Hyperactivity Disorder Rating Scale (ADHD-RS), secondly to present national norm scores compared to that of United States and other European data and thirdly to evaluate ADHD-RS when used for monitoring treatment effectiveness. METHODS: A Danish translation of the ADHD-RS was used on a normative sample of 837 children. Two clinical samples, 138 hyperkinetic disorder (HKD) cases and 110 clinical controls were recruited from eleven Danish Child and Adolescent Mental Health (CAMH) centres and assessed according to usual clinical standards. The HKD children were rated by parents and teachers at baseline and at follow-up 3 months later. RESULTS: Internal validity of ADHD-RS was high and the factor structure supported the diagnostic classification system ICD-10. The questionnaire discriminated HKD patients in a mixed clinical sample, and was sensitive to change in symptom load as measured before and after commencing of the treatment. CONCLUSION: The Danish version of ADHD-RS is valid and clinically feasible when measuring HKD symptom load in a CAMH-setting. The questionnaire provides useful data in patient management, quality improvement and service planning as well as in effectiveness studies of different interventions for patients with HKD and related disorders in routine clinical settings.