OBJECTIVES: To provide information on financial, social and mental burden borne by the families of children with ADHD. METHODS: A pilot-tested questionnaire was sent to all members of the Flemish ADHD society. Data are collected on disease severity (IOWA-CRS (Conners Rating Scale)), health care utilization, use of social care and other non-medical resources; and on socio-demographic and economic characteristics of the parents. Data of the ADHD-children are compared with data of their siblings, for which similar data are collected. RESULTS: A total of 656 questionnaires were returned (response rate 38.5%), however, the IOWA-CRS was completed in only 379 questionnaires. The mean age of the children with ADHD is 10.04 (range 3-16) and mean age at diagnosis is 7.04 (range 2-14). 22.7% of the ADHD-children exhibit a score below 15 on the IOWA-CRS, 54.06% have a score between 15 and 22 and 22.7% suffers from a severe form of ADHD with a score above 22 (maximum 30). The resource use of an ADHD-child is significantly higher compared to their siblings. Using McNemar tests we found that ADHD-children are significantly more likely to have emergency department visits (20.4% vs. 6.8%) and specialist visits (22% vs. 3.2%). The severity of the disorder is positively related to medication and specialist use (Wilcoxon Signed Rank Test). Parents stay significantly more often home from work for their ADHD-child (10.6% vs 2.4%) and significantly more children with ADHD miss a year at school (17.2% vs. 4.3%) or go to a special school for children with learning disabilities (10% vs. 0.9%). CONCLUSION: Childhood ADHD results in significantly higher use of health care and adversely affects school attainments and parents' productivity. This puts a heavy burden on the family. Nevertheless we have to take into consideration we have used a non-random sample and that we used siblings as a comparator group.