Asthma is a global health problem and currently it is estimated that 300 million people are affected. The aim of asthma treatment is to achieve and maintain clinical control. OBJECTIVES: Conduct a cost-effectiveness analysis of budesonide/formoterol as maintenance and reliever therapy for treatment of moderate or severe persistent bronchial asthma. METHODS: A cost-effectiveness analysis was performed using a decision tree that compares two treatment alternatives: budesonide/formoterol (maintenance and reliever) vs. salmeterol/fluticasone (maintenance) plus salbutamol (reliever). Efficacy data was obtained from scientific literature and direct medical costs was obtained from institutional sources. A deterministic and probabilistic sensibility analysis was performed to determine the robustness of the model. Two measures of effectiveness were used: Life Years Gained without hospitalization (LYGh) and Life Years Gained without severe exacerbation (LYGse). RESULTS: Budesonide/formoterol increases the time free from hospitalization (49.92 vs. 48.88 weeks) with an ICER (Incremental Cost-Effectiveness Ratio) of $7,541.51and the free-time of severe exacerbations (41.08 vs. 37.96 weeks) with an ICER of $3,322.86; both below the willingness to pay set in Mexico (1 GDP per capita: $10,047.00).The sensibility analysis showed consistency in results: budesonide/formoterol has a probability of 60% of being cost-effective in case of LYGh and 90% with LYGse efficacy measure vs. salmeterol/fluticasone under threshold ratio. CONCLUSIONS: The use of budesonide/formoterol as maintenance and reliever therapy is a cost-effective treatment in the Mexican Health system  compared to salmeterol/fluticasone plus salbutamol reducing the time without a severe exacerbation and time in hospitalization.