Currently, attention deficit hyperactivity disorder (ADHD) is intensively studied by world medical community, its understanding expands, for example, it has now been diagnosed not only in children but also in adults. On the other hand, ADHD raises a number of discussions on the need of its treatment and, if there is a need, how it shall be treated, it is doubtful whether this disorder overall exists, because its “morphological component” has not been identified so far, and all the symptoms of ADHD, including anxiety, concentration difficulties, motor hyperactivity, cognitive disorders or social disadaptation, can be found in a number of mental disorders and somatic diseases. Modern attention, emotional and behavioral changes can be considered as a result of changing human social portrait. Those who question ADHD existence argue that this disorder is likely temperament and parenting matter, rather than the illness, and that the diagnosis and treatment of this illness can be a matter invented by doctors and pharmacists, the aim of which is to tame individuals disregarding public standards of conduct and get the maximum profit from medicines in the treatment of this illness. Due to the fact that ADHD is diagnosed more often, it is even called the twenty-first-century scourge. In this article we will review the historical aspect of formation of ADHD diagnosis, illness etiology, comorbidity with other mental and somatic diseases as well as treatment necessity and opportunities, paying attention to adult ADHD as well.