Attention-deficit/hyperactivity disorder (ADHD) is a common impairing disease among children and adolescents. Methylphenidate, a stimulant, is effective in treating these patients. OROS methylphenidate (CONCERTA) provides ADHD patients a more convenient and safer treatment approach than immediate-release methylphenidate (IR-MPH). However, there is little information of long-term effect and adherence to CONCERTA. At the NTUH Taiwan, a randomized clinical trial of OROS MPH was performed 3 years ago and 64 subjects were included and treated with either IR MPH or OROS MPH followed by OROS MPH. Therefore, we purpose this study to follow up these patients, exploring the adherence rate to CONCERTA, symptoms evolution, and outcomes among these patients.