Attention deficit hyperactivity disorder is characterized by excessive overactiviy, inattention and impulsiveness. It is reported that attention deficit hyperactivity disorder affects 5-12% of children worldwide. It has significant negative effects on psychological and social development and academic functioning of the children if it remains  untreated. The etiology of attention deficit hyperactivity disorder is unknown. Genetic, neurodevelopmental, neurophysiological, and psychosocial factors are considered to play role in the etiology. There have been important improvements  in the treatment  strategies over the past years. In this review it was aimed to overview clinical characteristics, treatment strategies, and the course of the attention deficit hyperactivity disorder. (Turk Arch Ped  2011; 46 Suppl: 25-8)