Attention deficit hyperactivity disorder (ADHD) is often associated with symptoms of aggression in children and adolescents. Clinically, this is complex because aggression can be from hyperactivity and impulsivity, or could be a distinct symptom from a comorbid diagnosis. Past research has recommended first treating the primary disorder of ADHD. Stimulants are the most common treatment for pediatric ADHD, which can be helpful in decreasing aggressive behaviors. Alpha-adrenergic agonists and atomoxetine (ATX) are non-stimulant medications for ADHD and aggression, but more research is necessary to compare these drugs to stimulants. If aggressive symptoms do not improve from treating the primary disorder, aggression can be treated separately. Risperidone, lithium, valproic acid, clonidine, and guanfacine have shown positive results in reducing aggression, but studies including children with aggression and ADHD are limited. The variability in treatment tolerability in patients has stimulated research in pharmacogenetics for ADHD. Although this field is still emerging, research has found evidence supporting a link between the response rate of methylphenidate and the dopamine transporter (DAT1) and a link between the metabolism rate of atomoxetine and hepatic cytochrome 450 isozymes. Pharmacogenetics may be relevant to ADHD and associated aggression. Further research in pharmacogenetics will strive to identify patterns of genetic variations that can tailor individual treatments.