In an open randomised parallel-group study, 1004 patients with asthma in 7 countries were randomised to receive asthma treatment via 2 different kinds of inhalers: an aerosol pressurised metered dose inhaler (pMDI) and a dry powder inhaler (Turbuhaler). The patients were treated for 52 weeks with inhaled corticosteroids and/or inhaled beta 2-agonists. All patients were considered adequately treated with inhaled corticosteroids and/or inhaled beta 2-agonists via pMDI before inclusion in the study. Healthcare utilisation variables were attached to the case record forms of the patients, thus making an economic analysis possible. Because of the difficulty of comparing costs between countries, each country was analysed separately. Canadian patients constituted the largest subpopulation (445 patients) and were therefore used in this analysis. From the analysis, we concluded that the effectiveness of treatment (measured as the number of exacerbations and days with exacerbation) was significantly better for patients treated via Turbuhaler than via a pMDI (p = 0.03). Furthermore, the total annual costs of treatment were, on average, $Can331 less (p < 0.01) for patients using Turbuhaler than for those using a pMDI (mainly due to lower costs for hospitalisation and medication). The cost differences between inhaled corticosteroids and inhaled beta 2-agonists were significantly in favour of treatment via Turbuhaler (p < 0.01). Thus, the results of this study suggest that treatment via Turbuhaler is a cost-effective strategy in patients with asthma in Canada.