Aim. To compare the self concept of boys with ADHD and health subjects; to determine which symptoms of ADHD, oppositional defiant disorder (ODD) or conduct disorder (CD) have the greatest impact on self-concept. Method. Polish version of The Harter Self-Esteem Questionnaire (HSEQ) was filled by boys with ADHD and control group. In addition, a diagnosis of ODD and CD was made in ADHD group. Results. A significant difference was observed between boys with ADHD and control group on the following scales of HSEQ: Global Self-Esteem Subscale, Social Acceptance Subscale and Scholastic Performance Subscale. No significant influence of the quantity and intensity of ADHD and ODD symptoms on self-esteem was found. A significant correlation was indicated between all scales of HSEQ and quantity and intensity of symptoms of ADHD. Conclusions. Boys with ADHD have lower self-esteem than their healthy peers and their global self-esteem, social acceptance and school skills are most affected. The presence of conduct disorder (CD) had the greatest impact on the decrease of self esteem in ADHD group.