ADHD is one of the most common disorders that occur in children and adolescents. The cause of this disorder is still unknown and insufficiently researched, but various researches revealed which factors could possibly influence the development of this disorder. The main symptoms of this disorder are inattention, hyperactivity and impulsivity. Those three are the most visible symptoms of ADHD and they always somehow intertwine with each other. In order to diagnose ADHD, it is necessary that the conditions from the Diagnostic and Statistical Manual for Mental Disorders are met. In order to be diagnosed ADHD, symptoms must be present before the child is seven years old, they must last at least six months and must appear in two different environments, either in kindergarten or at home. The diagnostic procedure aims to gather as much information as possible about the child from many different sources. A team consisting of pediatricians, neuropediatricians, speech therapists, and psychologists participates in the diagnosis, and they receive information from parents and educators. Once the diagnosis is established, the treatment begins. Treatment is only intended to alleviate symptoms and reduce specific difficulties. The first step in treatment is psychoeducation, followed by drug therapy. There are also other forms of treatment, such as neurofeedback. As children with ADHD are mostly misunderstood while growing up, ignoring this disorder is not good because it can have devastating consequences for the child. It is essential that the child's immediate environment, especially the parents and educators, accept that the child has a disorder, start treatment on time, and be full of understanding and support for the child so that he can fit into everyday life without any problems.