Attention deficit/hyperactivity disorder is one of the most comminly treated conditions in the child psychiatric units and results in substantial impairment in peer, family and academoc functioning. For 70% to 80% of children with a diagnosis of ADHD, stimulant tratment results in successful improvement of the core ADHD symptoms. However, children with ADHD have high level of comorbidity and may respond differently from children with ADHD without comorbidity. Therefore they may need specific treatment plan. We reviewed efficacy and safety of prescribed medication for treating children with ADHD, the relationship between ADHD and the comorbid conditions and treatment algorithm projects of ADHD with/without comorbid conditions performed Korean and American child psychiatrists. Our main objective is to increase the uniformity of treatment and improve the clinical outcomes of children with comorbid ADHD.