Attention deficit hyperactivity disorder (ADHD) is still underdiagnosed in many EU countries. Despite its relevance in terms of public health, the incidence and prevalence of this disorder is not well researched.

The national incidence and prevalence of ADHD diagnosis in children and adolescents has not yet been reported in any South Eastern European country.

The main aim of this study was to investigate the incidence and prevalence of ADHD diagnosis among children and adolescents in Slovenia in 2012, based on national data from 1997 to 2012. Different epidemiological models were built.

The data from the National Institute of Public Health of the Republic of Slovenia for the years 1997–2012 were analyzed. The yearly database includes all newly diagnosed outpatients with ADHD in Slovenia.

In 1997, the annual incidence rate of ADHD diagnosis was 0.0317 % and increased to 0.0469 % in 2000 and to 0.0823 % in 2012. The prevalence rate of ADHD diagnosis was estimated between 722 and 767 per 100,000 children and adolescents. If the increase persists, the prevalence of ADHD diagnosis in 2020 will be 6.3-fold higher than in 1997 and 1.3-fold higher than in 2012.

ADHD is a common mental health disorder in Slovenia, but it is still underdiagnosed in comparison with Western countries. Results indicate a need for improved timely interventions in Slovenia, not only in child and adolescent psychiatry but also in primary settings and adult psychiatry, where ADHD should be recognized efficiently.