Attention deficit/hyperactivity disorder (ADHD) is a condition characterized by persistent inattention and hyperactivity-impulsivity, expressed to a degree that interferes with a patient's functioning or development. It is one of the most common neuropsychiatric disorders, with a prevalence of 3-5 % in childhood, and it can also persist into adulthood. The prevalence of ADHD among adults is estimated to be 2.5-4.5 %. The development of ADHD is linked to various genetic, neurophysiological and environmental factors, such as genetic inheritance, the child's exposure to harmful substances in the prenatal period and early life and adverse events during pregnancy and childbirth. The symptoms of ADHD result from anomalies in white and gray brain matter and dysfunctions of the dopaminergic and noradrenergic neurotransmitter systems. Clinically, ADHD in adults is characterized by main symptoms of hyperactivity, impulsivity, attention deficit, emotional dysregulation and sleep difficulties. Numerous psychiatric and non-psychiatric comorbidities are often present as well. The diagnosis of ADHD is made according to the criteria described in the Diagnostic and Statistical Manual of Mental Disorders (5th edition) published by the American Psychiatric Association. In adulthood, there is often a reduced expression of ADHD symptoms, but the functional impairment and negative impact on numerous aspects of life continues. Treatment of ADHD in adults includes pharmacological and non-pharmacological methods and their combination, and is based on a multimodal and multidisciplinary approach. Drugs used in the treatment of ADHD can be classified into stimulants (methylphenidate and amphetamines) and non-stimulants (atomoxetine, bupropion, tricyclic antidepressants, clonidine, guanfacine), while an example of a non-pharmacological method of treatment is cognitive behavioral therapy. When treating adult patients with ADHD, special attention must be paid to the specifics of treatment for pregnant women and the elderly, as well as the potential for drug abuse and strategies for abuse prevention.