Oppositional defiant disorder (ODD) consists of an enduring pattern of uncooperative, defiant and hostile behaviour toward authority figures that does not involve major antisocial violations and is not accounted for by the developmental stage of the child. The rate of ODD in children and adolescents in the general population has been reported to be between 2% and 16%. The International Classification of Diseases 10th Revision (ICD-10) classifies ODD as a mild form of conduct disorder (CD), and it has been estimated that up to 60% of patients with ODD will develop CD. Therefore, ODD should be identified and treated as early and effectively as possible.In more than one-half of patients with attention-deficit hyperactivity disorder (ADHD), ODD is also part of the clinical picture. There is strong evidence in the literature to suggest that ODD and ADHD overlap; many medications that are used to treat ADHD may also be efficacious in the treatment of ODD. A few studies have reported the positive effects of psychostimulants or atomoxetine in the treatment of ODD associated with ADHD. Patients with ODD and CD with severe aggression may respond well to risperidone, with or without psychostimulants. Mood regulators, alpha(2)-agonists and antidepressants may also have a role as second-line agents in the treatment of ODD and its co-morbidities.