OBJECTIVES: To determine the relative cost-effectiveness of the inhaled corticosteroids beclomethasone dipropionate (BDP), budesonide (BUD), and fluticasone propionate (FP), for managing moderate to severe asthma in adults over a one year time horizon from the perspective of the Ministry of Health (MOH) in Canada. METHODS: A single-arm meta-analysis of randomized control trials containing at least one of FP, BUD and BDP was performed in order to derive estimates of effectiveness and tolerance. A decision tree analysis was then used to model the cost-effectiveness analysis. Only direct medical costs were included in the analysis (i.e. inpatient care, emergency visits, physician services, nursing services, drugs, diagnostic tests). The time horizon of the study was 52 weeks, precluding discounting. All costs are presented in 1996 Canadian dollars (CDN$). The cost-effectiveness was the cost per additional symptom-free day ($/SFD). RESULTS: 69 of 398 articles were included in the meta-analysis. The Monte Carlo base case analysis showed that FP and BUD resulted in an annual cost of $1383 and $1147 respectively (p<0.01). FP produced 216 SFDs while BUD resulted in 214 SFDs, which were not significantly different at p=0.01 (a corrected for multiple comparisons). BDP cost $1343/year and yielded 213 SFD/year (BDP was excluded from the final analysis, dominated by BUD) With no difference in effectiveness, a cost-minimization analysis showed that BUD was the cost-effective alternative costing $236 CDN less than the FP strategy. CONCLUSIONS: Of the inhaled corticosteroids available on the MOH Formulary in Canada, BUD is a cost-effective alternative for the treatment of adults with moderate to severe asthma.