In New Zealand about 20% of adults have asthma, 60% with mild disease. Guideline-based treatment of mild asthma is regular inhaled corticosteroids (ICS), with a short-acting beta agonist (SABA) as a separate inhaler used when needed for symptom relief. The benefits of regular ICS use are limited in actual clinical practice by poor ICS adherence and low prescription rates. We propose a 12 month randomised controlled trial recruiting 890 patients with mild asthma to determine if a novel regime of a combination ICS/fast onset long-acting beta agonist inhaler taken as required for relief of symptoms is superior to regular ICS therapy with SABA as required. This study has the potential to change practice in New Zealand and internationally and to improve outcomes in patients with mild asthma who have a poorly recognised and important burden of disease.