OBJECTIVES: To perform a cost-effectiveness analysis of the use of botulinum toxin type A (Dysport® vs Botox®) in the spasticity treatment in México METHODS: Dysport® and Botox® are two preparations of botulinum type A toxin commercially available at present. The units used to quantify the toxin activity in both products are different, but literature review indicates that equivalence in clinical effects is reach at a 1:2.5 ratio approximately between Botox® and Dysport®. Doses and use of resources for the spasticity treatment were estimated from an institutional perspective, through an algorithm based on observations performed in a specialized health care unit, and validated by independent neurological specialist. It was assumed that patient treatment process is similar with any of the botulinum toxin formulations. The cost estimated include: the treatment with Botox® or Dysport® and physical therapy. Costs were estimated in 2006 Mexican pesos and converted to dollars at an exchange rate of 1 USD to $10.91 Mexican pesos. The time horizon of analysis was 1 year. A sensibility analysis varying the dose relation between Botox® and Dysport® was performed. RESULTS: The estimated annual treatment cost were USD $3,481.94 for Botox and USD $3,116.96 for Dysport. Therefore, using Dysport represents an anual saving of MX$3,982 in the base case scenario. Increasing the dose relationship from 1:2.5 to 1:3 and 1:4 still showed annual treatment savings in favour of Dysport for USD $260.77 and USD $52.52 respetively. CONCLUSION: In the mexican contex, Dysport is a cost-minimization alternative for the treatment of patients with spasticity and this advantage is maintained in a dose range from 1:2.5 to 1:4