The present study focuses on Attention Deficit Hyperactivity Disorder (ADHD) and its comorbidity with Disruptive Behaviour Disorders (BD), examining their nosological comorbidity profile and analyzing the cognitive, clinical and sociodemographic variables in ADHD cases that are relevant to an increase in the probability of developing BD, which includes oppositional defiant disorder and dissocial disorder, according to the DSM-IV criteria (APA, 1994, 2002).