Aggression is a common symptom of many psychiatric disorders including attention deficit hyperactivity disorder, oppositional defiant disorder, conduct disorder, Tourette's disorder, mood disorders (including bipolar disorder), substance-related disorders, alcohol-related disorders, mental retardation, pervasive developmental disorders, intermittent explosive disorder and personality disorders (particularly antisocial personality disorder). Many forms of organic brain disorders may present with aggressive behavior. Aggression is common in some epileptic patients and some endocrinological diseases (e.g., diabetes and hyperthyroidism) may be associated with aggressive behavior. Physicians need to rule out many medical and psychiatric disorders before diagnosing aggressive behavior. A thorough diagnostic work up is the most important step in determining the nature of comorbid disorders associated with the behavioral problem. Structured interviews and rating scales completed by patients, parents, teachers and clinicians may aid the diagnosis and provide quantification for the change process related to treatment. The integration of medication, individual and family counseling, educational and psychosocial interventions including the school and community, may increase the effectiveness of interventions. Due to the common association of aggression and disruptive behaviors with attention deficit hyperactivity disorder, psychostimulants including new generation long-acting medications and other nonstimulant medications are considered the drug of choice for managing aggressive behavior and disruptive behavior disorders. Severe aggressive behavior not responding to these medications may require the single or combined use of mood regulators including lithium and/or antispychotic medications. Drugs such as risperidone (Risperdal®, Janssen-Cilag) have documented effectiveness and safety in children and adolescents, and can be used in treatment.