Background: Asthma management may involve a step up in treatment when symptoms are not well controlled. We examined whether budesonide/formoterol maintenance and reliever therapy (MRT) is as effective as higher, fixed-dose budesonide plus as-needed terbutaline in patients requiring step-up from Step 2 treatment (low-dose inhaled corticosteroids), stratified by baseline reliever use. Methods: A post-hoc analysis utilized data from three clinical trials of 6-12 months' duration. Patients aged >= 12 years with symptomatic asthma uncontrolled despite Step 2 treatment were included. Severe exacerbation rate, lung function and reliever use were analysed, stratified by baseline reliever use (2 occasions/day). Results: Overall, 1239 patients were included. Reductions in severe exacerbation rate with budesonide/formoterol MRT versus fixed-dose budesonide were similar across baseline reliever use levels, and were statistically significant in patients using 1-2 (42%, p = 0.01) and >2 (39%, p = 0.02) reliever occasions/day, but not2 reliever occasions/day (-0.33 and -0.74 occasions/day, respectively). Conclusions: Treatment benefit with budesonide/formoterol MRT versus higher, fixed-dose budesonide plus short-acting a2-agonist was found in Step 2 patients with relatively low reliever use, supporting the proposal that budesonide/formoterol MRT may be useful when asthma is uncontrolled with low-dose inhaled corticosteroid.