Attention Deficit Hyperactivity Disorder (ADHD) is a chronic and incapacitating mental disorder characterized by overactivity, inattention and impulsiveness. The syndrome is usually diagnosed in childhood and it continues into adulthood. However, because the symptoms of ADHD frequently overlap with other categories of psychopathology, in adults it is often underdiagnosed or neglected, and left untreated. This paper emphasizes the importance of recognizing this syndrome in adulthood. To this end, we provide a review of the literature and four illustrative cases of our own. Appropriate treatment is also discussed. (Int J Psych Clin Pract 2000; 4:35-39).