OBJECTIVE: To study the effectiveness and safety of budesonide/formoterol (Symbicort) Maintenance And Reliever Therapy (Symbicort SMART, AstraZeneca, Södertalje, Sweden), a simplified management approach with one inhaler compared with conventional best practice (CBP) with multiple inhalers in patients with persistent asthma. DESIGN: Open-label randomised controlled parallel group trial, 6-month treatment. PARTICIPANTS: A total of 908 patients > or = 12 years of age, with persistent asthma receiving treatment with inhaled corticosteroids (ICS), either alone or in conjunction with long-acting beta(2)-agonist. MAIN OUTCOME MEASURES: Time to first severe asthma exacerbation and number of severe asthma exacerbations. RESULTS: No difference between groups was seen in time to first severe exacerbation (p = 0.75). Exacerbation rates were low in both groups. A total of 12 patients in the Symbicort SMART group experienced a total of 14 severe asthma exacerbations, and 19 patients in the CBP group experienced a total of 25 severe asthma exacerbations (annual rate 0.07 vs. 0.13 p = 0.09). The mean daily dose of ICS expressed in BDP equivalent was significantly lower in the Symbicort SMART group (including as-needed use) vs. in the CBP group (749 microg vs. 1059 microg; p