Budesonide/formoterol (Symbicort), AstraZeneca plc) is a novel treatment for asthma, combining an inhaled corticosteroid - budesonide, and a long-acting beta(2)-agonist - formoterol, in a single inhaler, the Turbuhaler. Randomised, clinical studies in patients with asthma have demonstrated that budesonide/formoterol is more effective than the inhaled corticosteroids, budesonide and fluticasone alone, and at least as effective as both monocomponents in separate inhalers. Results from clinical studies suggest a synergistic effect when both drugs are administered via one inhaler, although the mechanisms for this are not fully understood. Budesonide/formoterol has a rapid onset of effect, apparent within 1 min of treatment, which is largely because of the properties of formoterol. Once- and twice-daily dosing with budesonide/formoterol are effective treatment options for patients with mild or moderate asthma. Studies have also shown that the beneficial safety profiles and dose relationships of both budesonide and formoterol allow dose adjustments of budesonide/formoterol in response to variations in the patient's asthma. Findings from the budesonide/formoterol adjustable maintenance dosing programme, comparing fixed and adjustable, symptom-guided dosing regimens, demonstrate that patients achieve equally good asthma control with adjustable dosing (from one inhalation twice-daily to more than four inhalations twice-daily), but at a significantly lower overall drug load. Adverse events, mainly expected inhaled corticosteroid and long-acting beta(2)agonist class effects, have been few in number and mild in nature. In addition, there is growing evidence that budesonide/formoterol is also effective in patients with chronic obstructive pulmonary disease. The future for treatment with budesonide/formoterol may include as-needed administration in addition to maintenance therapy.