The purpose of the study is to compare the efficacy of a flexible dose of Symbicort (budesonide/formoterol) with conventional stepwise best standard treatment in patients with persistent asthma.

Inclusion Criteria:

• Diagnosis of asthma >= 3 months
• Prescribed daily use of glucocorticosteroids for at least 3 months prior to Visit 1

Exclusion Criteria:

• Smoking history > 10 pack-years
• Asthma exacerbation requiring change in asthma treatment during the last 14 days prior to inclusion
• Any significant disease or disorder that may jeopardize the safety of the patient.

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