Attention-deficit/hyperactivity disorder (ADHD) is commonly known to occur during childhood, characterized by excessive inattention and/or hyperactivity and impulsivity as well as lack of emotional self-control and motivation. The prevalence of adult ADHD in the general population is estimated to be between 2-5%. The aim of this review is to provide an overview regarding current controversies related to ADHD within the adult population. The concept of ADHD in adults has been questioned and criticized by professionals over the last years. Overall, adult ADHD is well evidenced based on epidemiological data, genetic data, neuroimaging, psychosocial impairment and treatment effectiveness. Although, research within this field has been significantly improved, suggestions for future research are provided, in order to be able to clarify the remaining questions regarding this disorder throughout adulthood. One of the most important changes to be made in the near future should be to increase educational training on ADHD in adults.