Inclusion Criteria

• Must give written informed consent (IC) prior to participation in the study. For subjects 12 - 17 years of age, the IC must be signed parent or legal guardian. Females must sign the Women of Childbearing Potential Addendum
• Be willing and able to comply with the study procedures and visit schedules
• Male or female, at least 12 years of age
• Females 12-60 years of age must have a negative serum pregnancy test at Visit 1 (V1)
• Women of child bearing potential must be using an acceptable method of birth control
• Must have a documented diagnosis of asthma for a min. of 6 mos. prior to V1
• At V1, the subject must demonstrate a baseline FEV1 within >45% and <75% of predicted for their height, age, gender, and race
• Following abstention from medications used to treat asthma, subject must demonstrate >12% reversibility of airflow obstruction within 15-30 min. following inhalation of 180 µg (2 actuations, 90 µg ea.) of racemic albuterol MDI
• Must have stable baseline asthma and have been using a B-adrenergic agonist, and/or anti-asthma anti-inflammatory medication, and/or OTC asthma medication for at least 6 mos. prior to V1
• Must be in good health with the exception of their reversible airways disease and not suffering from any chronic condition that might affect their respiratory function
• Must have a chest X-ray that is not diagnostic of pneumonia, atelectasis, pulmonary fibrotic disease, pneumothorax, chronic obstructive pulmonary disease, etc.
• Must be able to complete the diary cards and medical event calendars reliably on a daily basis and demonstrate how to use the MiniWright PEF meter

Exclusion Criteria

• Subject who is expected to require any disallowed medications
• Female subject who is pregnant or lactating
• Subject who has participated in an investigational drug study within 30 days prior to V1, or who is currently participating in another clinical trial
• Schedule prevents him or her from taking the first daily dose of study medication and/or starting study visits before 9AM
• Subject who has travel commitments during the study that would interfere with trial measurements or compliance or both
• Subject who has a history of hospitalization for asthma within 45 days prior to V1, or who is scheduled for in-patient hospitalization during the trial
• Have a known sensitivity to levalbuterol or racemic albuterol, or any of the excipients contained in any of these formulations
• Subject using any prescription drug with which albuterol sulfate administration is contraindicated
• Subject with currently diagnosed life-threatening asthma
• Subject with clinically significant abnormalities that may interfere with the metabolism or excretion of the study drug
• Have a history of cancer (exception: basal cell carcinoma in remission)
• Have hyperthyroidism, diabetes, hypertension, cardiac diseases, or seizure disorders not well controlled by medication or that may interfere with the successful completion of this protocol
• Have a history of substance or drug abuse within 12 mos. preceding V1 or a positive urine drug screening at V1
• Have greater than 10 pack year history of cigarette smoking or use of any tobacco products within 6 mos. of V1
• Have a documented history of bronchopulmonary aspergillosis or any form of allergic alveolitis
• Have suffered from a clinically significant upper or lower respiratory tract infection in the 2 weeks prior to V1
• Have any clinically significant abnormal laboratory values
• Have a clinically significant abnormal 12-lead ECG that may jeopardize the subject's ability to complete study
• Subject who is a staff member or relative of a staff member