The aim of this investigation was to assess how different levels of intensity of ADHD symptoms influence the development of the subjective feeling of competence in school age children. The sample was comprised of 62 children age 11 to 13. For the purpose of estimation of the subjective feeling of competence, The Feeling of Competence Questionnaire was created. Level of ADHD symptoms intensity was estimated with the use of The Symptoms of ADHD Questionnaire, created on the basis of diagnostic criteria for ADHD included in DSM-IV and ICD-10. Cluster analysis distinguished two groups of children: a group with a lower level of ADHD symptoms intensity (Group 1) and a group with a higher level of ADHD symptoms intensity (Group 2). Group 2 revealed a significantly lower level of global feelings of competence and lower scores on the subscales: adaptive properties, knowledge and skills, acknowledgement, emotional factor and belief in success. There was no significant difference in the level of the feeling of co-operation skills and social adjustment. The results suggest that children with symptoms of ADHD are likely to have a low level of feelings of competence, which may well be a risk factor leading to later social disorders. (Contains 5 tables and 1 figure.)