The purpose of this protocol is to investigate the acute treatment efficacy, safety, and tolerability of atomoxetine on a once-daily dosing strategy in Taiwanese children and adolescents with ADHD.

Inclusion Criteria:

• Subject must have ADHD that meet DSM-IV disease diagnostic criteria as well as severity criteria
• Subjects must be aged 6 to 16 years
• Subjects must not have taken any medication used to treat ADHD or they must have completed the washout procedures
• Subjects must be able to swallow capsules
• Subjects must be of normal intelligence in the judgment of the investigator. Normal intelligence is defined as being without evidence of significant general intellectual deficit and expected to achieve a score of 80 or more if formal IQ testing were administered.

Exclusion Criteria:

• Weigh less than 20 kg or more than 60 kg at study entry
• Have a history of Bipolar I or II disorder, psychosis, or pervasive developmental disorder
• Meet DSM-IV criteria for an anxiety disorder as assessed by the investigator
• Have a history of any seizure disorder (other than febrile seizures) or prior ECG abnormalities related to epilepsy, or subjects who have taken (or are currently taking) anticonvulsants for seizure control
• Subjects who have a history of severe allergies to more than 1 class of medications or multiple adverse drug reactions.