The purpose of this study is to compare the efficacy and safety of a variable dose of Symbicort with a high fixed maintenance dose of another asthma medication, Seretide, in the treatment of asthma.

Inclusion Criteria:

• Diagnosed with asthma since at least 6 months prior to first visit
• Prescribed daily use of glucocorticosteroids for at least 3 months prior to first visit
• At least one asthma exacerbation more than one but less than twelve months prior to first visit

Exclusion Criteria:

• Respiratory infection affecting asthma within 30 days before first visit
• Use of oral, rectal, or parenteral glucocorticosteroids for within 30 days before first visit
• Any significant disease or disorder that may jeopardize the safety of the patient

Additional inclusion and exclusion criteria will be evaluated by the Investigator.