OBJECTIVES: To estimate the cost-effectiveness of Abatacept in combination with Methotrexate (MTX) versus other biologic DMARDs in combination with MTX in patients with moderate to severe active Rheumatoid Arthritis. METHODS: A sequences treatment model was adapted for the representation of disability in terms of HAQ Index on a 5 year horizon for a cohort of 1000 patients. Abatacept in combination with MTX was compared with etanercept, rituximab, infliximab, adalimumab and tocilizumab, all of them associated with MTX. Currency is expressed in Peruvian soles (S/.) of 2010. RESULTS:  The cost of treatment with Abatacept resulted in S/. 169 263 and its effectiveness was found to be 1.96 QALY.  Regarding Etanercept, Adalimumab, Infliximab and Tocilizumab, Abatacept has shown to be the most effective in terms of QALYs and the least expensive. Regarding Rituximab, Abatacept has an incremental cost effectiveness ratio of S/. 75 493 per QALY gained. CONCLUSIONS: According to this model and inputs, Abatacept was found to be dominant against Etanercept, Adalimumab, Infliximab y Tocilizumab, from the Health Social Security (EsSalud) perspective for the treatment of moderate to severe active Rheumatoid Arthritis in patients who have failed to MTX based treatment.