OBJECTIVE: To assess the prevalence and burden of ADHD in the Nordic countries. METHODS: Literature databases were searched for publications relevant to the study countries and keywords. The time frame was 1987 to 2002. The keywords were ADHD, DAMP, MBD, and HKD. RESULTS: There were six prevalence studies in children aged between six and nine years. The prevalence rates of DAMP ranged between 2.8 and 7.1%. The prevalence rates of ADHD ranged between 3.7 and 7.1%. Several smaller Finnish studies reported that children with MBD/ADHD often transfer to special education, or require additional teaching at school. Finnish and Swedish studies found that 75-80% of children with MBD/ADHD don't complete high school. One Swedish study showed that 11% of children with ADHD had full sick pension at age 22. Finnish and Norwegian publications report that 38% - 47% of children with ADHD/MBD have no friends. Fifty-three percent of the parents in a Norwegian study said their marital problems were associated with the child's MBD. Finnish and Norwegian studies found that the child's dysfunction caused the family extra burden in daily activities and a change of their work situation or time. Swedish, Danish, and Finnish studies have shown that ADHD is associated with long-term psychiatric consequences. In Denmark, 24% of children with ADHD had been given a lifetime psychiatric diagnosis at age 23. Finnish, Norwegian, and Swedish studies have reported an over-representation of ADHD in prison populations. Moreover, children with ADHD are especially exposed to sexual offences, and commit such crimes more often than others. CONCLUSIONS: The Nordic data on prevalence of ADHD is in concordance with international figures. Although some of the studies were small and not randomised, the results indicate that ADHD is associated with a great burden for the affected children, their families, and the environment.