Asthma is characterised by chronic airway inflammation and variable airway obstruction. Maintenance therapy with inhaled corticosteroids and short-acting beta2 agonists on demand constituted the cornerstone of asthma management for many years. Since introduction of the long-acting form, beta2 agonists are currently also used as maintenance therapy. beta2 agonists and corticosteroids have complementary and synergistic effects in vitro and the combination also has increased efficacy clinically. The combination of long-acting beta2 agonists and inhaled corticosteroids is the treatment of choice in patients with moderately severe asthma whose symptoms persist despite inhalation of a corticosteroid. Currently, the combinations fluticasone-salmeterol and budesonide-formoterol are commercially available in one inhaler. Studies of these combined preparations are based on two contradictory treatment strategies: one in which the dosage is increased gradually in a controlled manner, and one in which a variable dose is added to a maintenance regime. Both strategies seem more effective than fixed low dosages of the same preparations. A well-founded choice between the two strategies cannot be made, if only due to the lack of knowledge regarding the effects of these strategies on treatment compliance, airway remodelling, side effects and costs.