Objective: Rituximab is a monoclonal antibody with demonstrated efficacy (REFLEX trial) in rheumatoid arthritis patients who responded inadequately to anti-TNF drugs (Cohen et al. 2006). The study assessed the total cost of rituximab therapy in comparison with infliximab, adalimumab, etanercept and abatacept under a private payer perspective in Brazil. A budget impact analysis was performed. Methods: This study assumed the same efficacy for all drugs, since there has not been any head-to-head trial available until now, although indirect comparisons show higher ACR response rates for rituximab. Direct annual medical costs for biological drugs, IV administration, weekly metotrexate (MTX) and routine exams were taken from a panel of Brazilian rheumatologists. Base case dosages considered were: rituximab (2g every 8 months), abatacept (750mg at weeks 0, 2, 4 and then every 4 weeks), infliximab (4mg/kg at weeks 0, 2, 6 and every 8 weeks), adalimumab (40mg every other week) and etanercept (50mg every week). Local administration costs were obtained from Scheinberg et al. 2005. Costs were reported in 2007 Brazilian Reais and discounted at a 5% rate in the BIA. Therapies were evaluated using a 5-year horizon. In order to assess uncertainty, one and two-way sensitivity analyses were performed. Results: In the base case scenario, rituximab therapy resulted in a total annual cost of R$46,388 per patient. Total annual costs per patient for the comparators were: R$79,394 for infliximab, R$90,831 for adalimumab, R$120,351 for etanercept and R$77,118 for abatacept. In the BIA, rituximab therapy resulted in total savings of R$94,201,413 in 5 years considering the population in the private healthcare system only. Results were sensitive to dosage schedule (rituximab, infliximab and abatacept) and drug costs. Conclusion: Results of this study suggest that therapy with rituximab is a dominant alternative for patients with rheumatoid arthritis in the Brazilian private health care system.