The purpose of the study is to compare the efficacy of a flexible dose of Symbicort with conventional stepwise treatment according to asthma treatment guidelines in patients with persistent asthma.

Inclusion Criteria:

• Minimum of 3 months history of asthma, diagnosed according to the American Thoracic Society (ATS) definition. Prescribed inhaled GCS at a dose of ³400 µg/day and within the approved label for the relevant drug during the last 3 months prior to Visit 1.

Exclusion Criteria:

• Use of any b-blocking agent, including eye-drops, Use of oral GCS as maintenance treatment, A history of smoking ³ 10 pack years (1 pack year = 1 pack (20 cigarettes) per day for one year or equivalent).