OBJECTIVES: The objective of this study is to estimate the Health Related Quality of Life (HRQoL) of ADHD children and the societal costs for the Netherlands. METHODS: An initial population of 10,000 children aged 6-8 years were rated by their schoolteachers to determine the probability of ADHD. A total of 150 children with low scores (low probability) and 150 with high scores were invited for a detailed prospective assessment of the burden of illness for patient and relatives. We collected data from the mother on health care utilization and HRQoL of 3 categories children, e.g. children in the community with high scores (group 1), clinical ADHD children (group 2) and controls with low scores (group 3), at 4 moments in time (baseline, t=6 months, t=12 months and t=18 months). The Child Health Questionnaire (CHQ-PF50) was used for measuring the HRQoL. Additionally, health care utilization and productivity loss of the mother of the respondents were assessed by using the Trimbos and iMTA questionnaire on Costs associated with Psychiatric illness' (TiC-P). RESULTS: At baseline, we distributed a total of 165 questionnaires for the 3 groups. The response rates were; group 1: 94% (n=33), group 2: 90% (n=64) and group 3: 78% (n=47) respectively. Of group 1, 33% of the respondents were identified as ADHD by a paediatrician. Except for physical function, group 2 (ADHD patients) scored significant worse on social and emotional functioning and the health care costs were higher than group 1 and 3. CONCLUSIONS: Children suffering from ADHD had worse HRQoL and higher health care costs than the controls.