Objective: Abatacept is a new biological DMARD with selective co-stimulation modulator mechanism of action that was recently approved in Brazil for the treatment of patients with moderate to severe RA. We aim to evaluate and describe the budget impact of the inclusion of abatacept in the National Program of Exceptional Medications (NPEM) with the tumor necrosis factor (TNF) antagonists currently in use and included. Methods: Using data provided by Brazilian Ministry of Health, our study estimates the cost associated with the inclusion of Abatacept for inadequate responders to methotrexate and TNF antagonists compared with actual scenario (without Abatacept). Our model presumes: adequate doses and regimen of abatacept (10 mg/kg. 0, 2, 4, and each 4 weeks), infliximab (4.2 mg/kg each dose of infliximab, 0, 2, 6, and each 8 weeks), etanercept (25mg each dose/twice a week) and adalimumab (40 mg each dose, twice a month), and we accept the actual distribution of TNF antagonists used by NPEM (with adoption of 20% of increase in the number of the RA patients each year – NPEM data). According to literature, 30% of the patients with inadequate response to methotrexate will be eligible to use abatacept, and we accept this percentage to introduce patients in the abatacept group. The initial population is 4978 patients currently in use of TNF antagonists in 2007. Results: In the first year of inclusion there is an increase in costs of R$3,085,711 (US$1,763,263). In the second and third years there are significant savings on budgets, R$97,593,971 (US$55,767,983) and R$129,458,357 (US$73,976,204), respectively. Conclusion: The incorporation of abatacept into the NPEM is cost-saving to the Brazilian Public Health System, saving R$129,458,357.00 (US$73,976,204) after the third year.