The FACET (Formoterol and Corticosteroid Establishing Therapy) study established that there is a clear clinical benefit in adding formoterol to budesonide therapy in patients who have persistent symptoms of asthma despite treatment with low to moderate doses of an inhaled corticosteroid. We combined the clinical results from the FACET study with an expert survey on average resource use in connection with mild and severe asthma exacerbations in the U.K., Sweden and Spain. The primary objective of this study was to assess the health economics of adding the inhaled long-acting beta2-agonist formoterol to the inhaled corticosteroid budesonide in the treatment of asthma. The extra costs of adding the inhaled beta2-agonist formoterol to the corticosteroid budesonide in asthmatic patients in Sweden were offset by savings from reduced use of resources for exacerbations. For Spain the picture was mixed. Adding formoterol to low dose budesonide generated savings, whereas for moderate doses of budesonide about 75% of the extra formoterol costs could be recouped. In the U.K., other savings offset about half of the extra cost of formoterol. All cost-effectiveness ratios are within accepted cost-effectiveness ranges reported from previous studies. If productivity losses were included, there were net savings in all three countries, ranging from Euro 267-1183 per patient per year. In conclusion, adding the inhaled, long-acting beta2-agonist formoterol to low-moderate doses of the inhaled corticosteroid budesonide generated significant gains in all outcome measures with partial or complete offset of costs. Adding formoterol to budesonide can thus be considered to be cost-effective.