Ages eligible for study: 12 years and above; genders eligible for study: both; prior steroid use: steroid-requiring.

Inclusion Criteria:

• History of asthma for at least 12 months.
• Documented use of inhaled corticosteriod for at least 4 weeks prior to Screening Visit Demonstrate FEV-1 of 40-80% of predicted normal values at Screening and Baseline Visit.
• Documented reversibility of 15% within 6 months of Screening Visit or at Screening Visit (15% increase from pre-FEV-1 levels following albuterol inhalation).
• Symptoms of Asthma during Run-in.
• Females of childbearing potential must have a negative urine pregnancy test at Screening and Baseline Visits. Females are eligible only if they are not pregnant or lactating and are either sterile or using acceptable methods of contraception.
• Must otherwise be healthy.
• Provide written informed consent. Wishes of minors must be respected.

Exclusion Criteria:

• Life-threatening asthma within past year or during Run-in Period.
• History of systemic corticosteroid medication within 3 months before Screening Visit.
• History of omalizumab use within the past 6 months.
• History of leukotriene receptor antagonist use, e.g., montelukast, within the past week.
• Current evidence of history of any clinically significant disease or abnormality including uncontrolled hypertension, uncontrolled coronary artery disease, congestive heart failure, myocardial infarction, or cardiac dysrhythmia.
• Upper or lower respiratory infection within 4 weeks prior to Screening Visit or during Run-in Period.
• Significant, non-reversible, pulmonary disease (e.g., chronic obstructive pulmonary disease [COPD], cystic fibrosis, bronchiectasis).
• Known Human Immunodeficiency Virus (HIV)-positive status.
• Smoking history equivalent to "10 pack years".
• Current smoking history within 12 months prior to Screening Visit.