Objective: To directly compare the efficacy of methylphenidate and atomoxetine in improving symptoms, social functions, and quality of life among adults with ADHD. Method: This was an 8-to-10-week, open-label, head-to-head, randomized clinical trial with two treatment arms: immediate-release methylphenidate (IR-methylphenidate; n = 31) and atomoxetine once daily (n = 32). The outcome measures included ADHD symptom severity, quality of life, and functional impairments. Results: We found a significant reduction in overall ADHD symptoms and improvement in social functions and quality of life for both groups at Weeks 4 to 5 and Weeks 8 to 10. There was no significant difference in the slope of improvements over time except that atomoxetine was superior to IR-methylphenidate in reducing hyperactive/impulsive symptoms at Weeks 4 to 5. There was no significant group difference in the rates of adverse effects. Conclusion: Both IR-methylphenidate and atomoxetine are well tolerated and efficacious in ethnic Chinese adults with ADHD. (J. of Att. Dis. 2013; XX(X) 1-XX)