Objectives: Agressive behaviours are an important associated developmental feature of attention-deficit/hyperactivity disorder (ADHD) and affect long term prognosis of ADHD. In this study, it's aimed to investigate the impact of sociodemographic variables, and variables related with the child such as verbal skills, the ability to decode facial expressions, social reciprocity skills and anxiety levels, on aggresive behaviours in children with ADHD. Methods: The study group consisted of 116 children between 7 and 11 year-old, who referred to a child psychiatry clinic, and were diagnosed with ADHD for the first time. A sociodemographic form, Turgay DSM-IV-Based Child and Adolescent Disruptive Behavioral Disorders Screening and Rating Scale (T-DSM-IV-Scale)-parent form, Social Reciprocity Scale (SRS), Child Behavior Checklist (CBCL), Screen for Child Anxiety Related Emotional Disorders (SCARED)parent form, Reading Mind in the Eyes Test were used for assessment. Diagnoses were established based on clinical interview, and supported by the Kiddie Schedule for Affective Disorders and Schizophrenia. Results: The mean age of children were 9.65 +/- 2.01. The CBCL aggressive behavior subscale score was correlated with the SCARED-parent form total score, SRS total score, and T-DSM-IV-Scale-parent form hyperactivity/impulsivity (H/I) subscale score. In multiple lineer regression analysis, the three control measures were found to be the predictive factors of aggressive behavior severity, with the mean score of T-DSM-IV-S H/I subscale recording a higher beta value than the SCARED Parent Form score, and SRS total score. Discussion: In children with ADHD, it is supposed that investigating the predictive factors, and implementing the preventive interventions before the appearance of aggressive behaviours will improve the prognosis of disorder.