Anxiety and mood disorders are frequently comorbid with attention-deficit/hyperactivity disorder (ADHD). In this report, the characteristics of anxiety and mood disorder [major depressive disorder (MDD) and bipolar disorder] were investigated in an attempt to identify differences that could potentially advance our understanding of treatment options for these comorbidities with ADHD. We reviewed studies which examined stimulant response in children diagnosed with ADHD/anxiety, depression and bipolar disorder. Recent research suggests that stimulants can be safely used in children with anxiety/depressive disorder comorbid with ADHD. Antidepressants may be used in conjunction with stimulants to treat MDD and anxiety, while mood stabilizers and atypical antipsychotics are often required to treat manic symptoms. After resolution of the comorbid manic episode, stimulant treatment of ADHD may be safely undertaken. Clinicians should be prepared to deal with a wide range of emotional problems beyond the core symptoms of ADHD.