Objective: This study systematically reviews the current literature on the administration of atomoxetine for treating children and adolescents with comorbidity on autism spectrum disorder (ASD) and ADHD. Method: PubMed/Medline and Google Scholar databases were electronically searched to find the published trials on atomoxetine and ASD. Results: Six articles reported the clinical trials of atomoxetine for treatment of ADHD symptoms in patients with autism or pervasive development disorders. Only one study that was placebo-controlled crossover pilot trial reported that it is effective. Atomoxetine may be effective in high-functioning patients with autism or patients with low severity. Those with high severity of ASD may be more vulnerable to the adverse effects of atomoxetine. Conclusion: There are not enough controlled clinical trials for showing the efficacy of atomoxetine for treatment of ADHD symptoms in autism. Although evidence suggests potential efficacy of atomoxetine, the current evidences are not conclusive. (J. of Att. Dis. 2012; XX(X) 1-XX)