AIM Attention deficit hyperactivity disorder (ADHD) and related disorders affect children's ability to function in school and other environments. Awareness has increased in recent years that the same problems often persist in adulthood. Based on previous studies, we aimed to outline and discuss a descriptive model for calculation of the societal costs associated with ADHD and related disorders. METHODS Following a literature review including childhood and adult studies, long-term outcomes of ADHD and associated societal costs were outlined in a simple model. RESULTS The literature concerning long-term consequences of ADHD and related disorders is scarce. There is some evidence regarding educational level, psychosocial problems, substance abuse, psychiatric problems and risky behaviour. The problems are likely to affect employment status, healthcare consumption, traffic and other accidents and criminality. A proposed model structure includes persisting problems in adulthood, possible undesirable outcomes (and their probabilities) and (lifetime) costs associated with these outcomes. CONCLUSIONS Existing literature supports the conclusion that ADHD and related disorders are associated with a considerable societal burden. To estimate that burden with any accuracy, more detailed long-term data are needed.