OBJECTIVES: Rheumatoid Arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints. Disease progression leads to a significant socioeconomic impact for the individual and for society. In Brazil, there are eight approved biologic drugs indicate to treat patients with moderate/severe RA that presented previous inadequate response to therapy with DMARDs, including tocilizumab (TCZ) and adalimumab (ADA). ADACTA trial (Gabay et al, 2012) showed positive results related to TCZ monotherapy for the treatment of moderate/severe RA in patients who presented inadequate response to methotrexate therapy or were MTX intolerant. This study aims to evaluate costs of TCZ monotherapy vs. ADA monotherapy to achieve remission after one year of treatment for adult RA, according to ACR70 and DAS28 outcomes. METHODS: An economic evaluation based on ADACTA study was performed. Drugs ex-factory prices were used to estimate treatment costs. Regimen was 8 mg/kg every 4 weeks TCZ and 40 mg every 2 weeks ADA. Costs to achieve remission in one year according to ACR70 and DAS28 outcomes were compared. The study was conducted from a Brazilian private health care perspective, considering only drug costs. Costs were reported in Brazilian Reais (BRL1.00=USD0.51 Feb/2013). RESULTS: Annual costs were BRL39,100.06 TCZ vs. BRL63,134.76 ADA. After one year of treatment, ACR70 response rates were achieved in 32.50% in TCZ group and 17.90% in ADA group. DAS28 remission was achieved in 39.90% and 10.50% in TCZ and ADA group, respectively. TCZ presented better results in costs per clinical remission than ADA (ACR70 BRL120,307.88 vs. BRL352,708.16 and DAS28 BRL97,995.14 vs. BRL601,283.43). CONCLUSIONS: TCZ presented better response rates in both ACR70 and DAS28 outcomes and lower annual costs per clinical remission compared to ADA, suggesting that TCZ is a better single-agent alternative to treat moderate/severe rheumatoid arthritis in Brazilian private health care system.