A guided, adjustable-dosing regimen with budesonide/formoterol was investigated in asthma patients. In a randomised, open, multicentre study, 1034 patients received budesonide/ formoterol (Symbicort, Turbuhaler,) 80/4.5 microg or 160/4.5 microg (depending on pre-study inhaled corticosteroid dose) two inhalations twice daily for four weeks, followed by adjustable or fixed maintenance dosing for six months. Patients receiving adjustable dosing stepped down to one inhalation twice daily if symptoms were controlled and could, if symptoms worsened, step up to four inhalations twice daily for one or two weeks according to a self-guided management plan. The primary efficacy variable was occurrence of exacerbations. Compared with fixed dosing, adjustable dosing was associated with fewer patients experiencing exacerbations (6.2% vs 9.5%, NNT 30, p<0.05), fewer daily inhalations of budesonide/formoterol (2.35 vs 3.95, p<0.001), lower costs (six-month saving Euros 98, p<0.001) and was similarly well tolerated. Adjustable maintenance dosing with budesonide/formoterol provides more effective asthma control than fixed dosing, and reduces costs.