The primary objective is to compare the effects of Symbicort SiT and treatment according to NHG-guidelines on bronchial hyperresponsiveness in asthmatic patients, as measured by PD20 histamine, and to validate the Bronchial Hyperresponsiveness Questionnaire (BHQ).

Inclusion Criteria:

• diagnosis of mild to moderate asthma, FEV1 ³ 60% of predicted normal values pre-bronchodilator, daily use of inhaled GCS during the last 3 months

Exclusion Criteria:

• Regular need of >4 inhalations of a short-acting b2-agonist/day, known or suspected hypersensitivity to any of the investigational drugs or inhaled lactose, use of any b-blocking agent, having smoked ³10 pack-years