The study is designed to investigate the acute treatment efficacy, safety, and tolerability of atomoxetine on a once-daily dosing strategy (in the morning). It incorporates a 6-week acute treatment period and a 2-week discontinuation phase. The assessments in this study include a standard assessment of ADHD symptomatology using a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition™, investigator-administered rating scale.

Inclusion Criteria

• Subjects must have ADHD that meets the DSM-IV criteria
• Aged 6 to 16 years.
• Subjects must not have taken any medication used to treat ADHD.
• Laboratory results must show no significant abnormalities
• Baseline ECG results must not show an abnormality
• Subjects must be able to swallow capsules.
• Subjects must be of normal intelligence.

Exclusion Criteria

• Weigh less than 20 kg or more than 60 kg at study entry.
• Subjects who, after an adequate trial with methylphenidate or amphetamine experience some benefit in ADHD signs and symptoms are excluded from participating.
• Have a history of Bipolar I or II disorder, psychosis, or PDD.
• Meet DSM-IV criteria for an anxiety disorder.
• Have a history of any seizure disorder.
• Patients at serious suicidal risk.
• Patients with narrow angle glaucoma
• Subjects who have a history of severe allergies .
• Have a history of alcohol or drug abuse within the past 3 months
• Screen positive for drugs of abuse not prescribed by a physician.
• Have cardiovascular disease and an increased heart rate and blood pressure.
• Have a medical condition that would increase sympathetic nervous system activity markedly or who are taking a medication on a daily basis.
• Have severe gastrointestinal narrowing
• Are during the study time likely to need psychotropic medications.
• Are likely to begin a structured psychotherapy aimed at ADHD symptoms.
• Have used a monoamine oxidase inhibitor (MAOI) during the 2 weeks
• Female subjects who are pregnant or who are breast-feeding.
• Are investigative site personnel directly affiliated with the study, or are immediate family of investigator site personnel directly affiliated with the study.
• Are, in the opinion of the investigator, unsuitable in any other way to participate in this study.
• Are employed by Lilly.