BACKGROUND: Asthma is a chronic disease with a heavy economic burden in terms of public health on account of its clinical impact and consequences on quality of life and costs. Its management is based on pharmacological measures with inhaled corticosteroids playing a large role. The objective of this study was to undertake an analysis of the published literature of medico-economic trials of the use of inhaled corticosteroids. METHODS: A review of the literature from 1990 to 2007 was undertaken with separate analyses of studies of inhaled steroids alone and those looking at combined preparations. RESULTS: The costs of asthma vary greatly depending on the clinical management. Analysis of the published clinical trials showed that the addition of inhaled steroids increased the total cost. When efficacy is taken into account the economic results are acceptable for developed societies. The use of inhaled steroids as maintenance therapy, or maintenance and symptomatic therapy, was always cost effective. CONCLUSION: These results are based on data from clinical trials. They need to be confirmed by large scale observational studies using validated criteria of effectiveness.