The main goal of this paper is to give the presentation of cognitions related to social integration difficulties of children with ADHD syndrome diagnosed, and the question which is to be answered is what are the difficulties, their manifestation, what are the reasons leading to those difficulties and ways to overcome it. The methods of searching, reading and elaborating available relevant professional literature of relevant experts will be implemented in this paper. During the search the following sources were being used: scientific portals (Hrčak, Google Scholar, and bib.ibr.hr), libraries of Rijeka university and Faculty of Philosophy, and public libraries of Rijeka city and Zagreb city. The cognitions being acquired by that research are grouped into following areas: family environment, preschool education system, school education system and relationship with peers. In a family environment, parents are declaring ADHD as "invisible difficulty", they are complaining about the bad relationship that society has towards children with ADHD diagnosed, and difficulties manifested by their children like impulsiveness, hyperactivity, and lack of attention are affecting the whole family which can lead to marriage crash. Some parents feel guilty and responsible for children behavior and, consequently, social determined. In the preschool education system children with ADHD diagnosed are manifesting the motor disorder, hastiness, lack of attention and impatience. It is not a rare case of children being "ejected" from preschool education institution in that age. The quality of educators is exceptionally important for achieving an appropriate level of children social integration. In the school education system, children with ADHD diagnosed are manifesting difficulties in following rules, work material organization, and group demands adjustments which can lead to deviant behavior and a feeling of loneliness. Children with ADHD are not favorites of peers because of their tendency to violent behavior, imposition of their own opinions, and lack of social skills. They often participate in peer violence as a victim. Support is possible through family therapy which includes both parents and the affected child. Determining the routine and providing optimal praise and reward to the affected child is of great importance. Besides that, a school can help in a way of making a special work plan for each child with ADHD with clearly determined methods and procedures of work.