This study evaluated the economic and health-related consequences of the as-needed use of a long-acting beta2-agonist with fast onset (formoterol, Oxis Turbuhaler 4.5 microg) versus a short-acting beta2-agonist (terbutaline, Bricanyl Turbuhaler 0.5 mg) in patients with moderate to severe asthma. A multi-national (Sweden, Norway, The Netherlands and Greece), multi-centre (35 centres), randomized, double-blind clinical trial was conducted using 362 patients on inhaled steroids during a 12-week period. The effectiveness results were pooled and the total costs included estimates for beta2-agonists, inhaled steroids, oral steroids, physician visits and sick-leave. The 182 patients in the formoterol group had 14,404 days of exposure and 29 severe exacerbations, and the 180 patients in the terbutaline group had 13,655 days of exposure and 48 severe exacerbations. The terbutaline group had 62% more severe exacerbations than the formoterol group (P=0.039), based on exposure time. Per patient, the calculated total costs were SEK 3386 for the formoterol group and SEK 3709 for the terbutaline group over the 12-week period. The conclusion is that the use of Oxis Turbuhaler instead of Bricanyl Turbuhaler for as-needed treatment is a more effective treatment generating cost savings from a societal perspective.