The objective of this study is to compare the effect of Concerta (Osmotic Release Oral System Extended Release Methylphenidate HCL, OROS MPH) and Strattera (Atomoxetine) on the laboratory and ecological executive function in children with attention deficit hyperactivity disorder.

The sample will include 134 ADHD children and adolescence, randomized assigned to Concerta and strattera treatment group, with 67 cases in each. It will also include 67 sex and age matched normal control. The drug will be titrated to optimal dose. The executive function including inhibition, working memory, set shifting and plan will be compared among two medication group and the control group, using laboratory executive function test and Behavior Rating Inventory of Executive Function (BRIEF).

Inclusion Criteria:

• Age between 6 to 16 years old. Body weight between 20 to 60 kg
• Meet ADHD criteria in tne Diagnostic and Statistic Manual of Mental Disorders, fourth edition (DSM-IV) through questionaire and interview
• Intelligence quotient (IQ) >= 70
• Currently unmedicated or effectively medicated with immediately released methylphenidate (The maximum dosage no more than 60mg/d)
• The patient and the parent express their will to comply with the follow up including the clinical interview and all the test
• The parent or the guardian sign the written consent
• Can swallow the capsule

Exclusion Criteria:

• Have administered immediate release methylphenidate, OROS MPH or atomoxetine, but ADHD symptoms not improved.
• Bipolar I or II disorder, psychosis, or pervasive developmental disorder.
• Meet the DSM-IV anxiety disorder.
• Any seizure disorder (except for febrile convulsion) or electroencephalogram (EEG) abnormal associated with epilepsy, or currently taking anti-convulsion drugs.
• Depression disorder, tend to commit suicide, or comorbid depression symptoms which need immediate treatment.
• Tics disorder, or Tourette's syndrom（DSM-IV 307.23）, or family history of tics disorder.
• Narrow-angle glaucoma
• cardiovascular diseases, or any diseases may be deteriorated when the pulse or the blood pressure increased, including hypertension or those taking anti-hypertension drugs.
• Diseases significantly enhance the sympathetic nervous system activity, or taking sympathomimetic drug every day.
• Allergic to methylphenidate or atomoxetine, or serious allergic reaction to more than one drugs or adverse event to multiple drugs before.
• Serious gastrointestinal stenosis
• History of alcohol, drug or other substance abuse
• Those using unprescribed potential abuse drugs in screening.
• In the process of the trial, the patient need to take other psychotropic drug other than the experimental drugs, including health food with central nervous system (CNS) activity (e.g. melatonin).
• Might begin any structure psychological therapy addressed for ADHD in the process of the trial
• Have used other psychotropic drugs in the past 30 days, including monoamine oxidase inhibitor.
• Are participating other clinical trial.
• Have difficulty in following up in 8 weeks.
• Relatives of the investigator.
• Employee of Xi-an Jensen or Eli lilly company.