Inclusion_Criteria:

1. Patients homozygous for arginine at the 16th amino acid position of the beta2 adrenergic receptor (B16 Arg/Arg)
2. All patients must sign and date an Informed Consent Form for the study prior to participation in the trial
3. Male or female outpatients with at least 18 years of age, but not older than 65 years
4. Patients must have a documented history of asthma
5. Patients must be current non-smokers or ex-smokers with a cigarette smoking history of <10 pack-years
6. Patients must be on a maintenance treatment with inhaled corticosteroids with a total daily dose of 400 - 1000 mcg budesonide or equivalent

Exclusion_Criteria:

1. Patients with a significant disease other than asthma
2. Patients with a recent history (i.e., six months or less) of myocardial infarction
3. Patients who have been hospitalized for heart failure (New York Heart Association class III or IV) within the past year
4. Patients with any unstable or life threatening cardiac arrhythmia or cardiac arrhythmia requiring intervention or a change in drug therapy within the past year
5. Patients with malignancy for which the patient has undergone resection, radiation therapy or chemotherapy within the last five years. Patients with treated basal cell carcinoma are allowed.
6. Patients with a diagnosis of chronic obstructive pulmonary disease (COPD)
7. Patients with a history of life threatening pulmonary obstruction, or a history of cystic fibrosis or clinically evident bronchiectasis
8. Patients with known active tuberculosis
9. Patients who have undergone thoracotomy with pulmonary resection.
10. Patients who have completed a pulmonary rehabilitation program in the six weeks prior to visit 1 or patients who are currently in a pulmonary rehabilitation program that will not be maintained throughout the duration of the study.