OBJECTIVES: Rheumatoid arthritis (RA) is a chronic, progressive, inflammatory disease that affects physical functioning and quality-of-life and is associated with premature mortality and substantial economic burden. We aimed to assess cost-effectiveness of tocilizumab added to disease-modifying antirheumatic drugs (DMARD) in patients with active RA despite DMARD therapy from the Mexican public health care system perspective. METHODS: Two models were designed to compare tocilizumab 8 mg/kg every 4 weeks; infliximab 3 mg/kg (weeks 0, 2, 6, 14 and 22); etanercept 25mg twice a week and adalimumab 40mg every other week. First model included only 6-month acquisition costs of drugs and infusion-related cost for infliximab and tocilizumab; the second was a Markov model with four states defined according to Disease Activity Score (DAS-28). Indirect comparison techniques were needed to adjust American College of Rheumatology (ACR) responses rates found in 10 clinical trials with biological agents. ACR70 at week 24 and overall days spent in remission during 5 years were main outcomes. Unit costs of medications were gathered from public bids; an expert panel was constituted to estimate 3-month resource use by health state. All costs are expressed in 2009 US dollars. RESULTS: First six-month costs were lower with tocilizumab (USD$4418) than with etanercept (USD$5,020), infliximab (USD$5484) and adalimumab (USD$5655). Adjusted ACR70 response rate was higher for tocilizumab than for anti-tumor necrosis factor (TNF) agents: 26% vs. 19%, 18% and 12% for adalimumab, etanercept and infliximab, respectively. Markov model estimates show savings of USD$623 up to USD$1321 per patient treated with tocilizumab instead of anti-TNF. Tocilizumab was also associated with mean gains of 9, 12 and 20 days in remission compared to etanercept, adalimumab and infliximab. CONCLUSIONS: When used instead of anti-TNF agents, add-on treatment with tocilizumab brings both health benefits and cost-savings for RA patients with inadequate response to previous DMARD therapy.