OBJECTIVES: ADACTA trial (Gabay C et al EULAR June 2012) showed that tocilizumab (TCZ) monotherapy was superior to adalimumab (ADA) monotherapy in reducing signs and symptoms of adult rheumatoid arthritis (RA) patients who were either intolerant to methotrexate (MTX) or for whom continued MTX treatment was inappropriate. The aim of the current study was to develop a cost-effectiveness analysis of TCZ vs. ADA in MTX-intolerant/contraindicated patients. METHODS: Economic evaluation based on ADACTA study was conducted to estimate the incremental cost-effectiveness ratio (ICER) of TCZ vs. ADA. Time horizon was 24 weeks.  Patient’s response in the model was measured through ACR response (ACR20/ACR50/ACR70) and DAS28 remission. Results were presented as incremental cost of TCZ vs. ADA per response. The analysis was conducted from the perspective of the Spanish National Healthcare System, considering drug costs. Unitary costs (€, 2012) were obtained from a Spanish database. Simple univariate sensitivity analyses were performed. RESULTS: ACR20 response rates were achieved in 65% and 49.4% in the TCZ and ADA group respectively (p<0.01).  ACR50 response rates were achieved in 47.2% and 27.8% in TCZ and ADA group (p<0.01) and ACR70 response rates in 32.5% and 17.9% in TCZ and ADA group (p<0.01) respectively. DAS28 Remission was achieved in 39.9% and 10.5% in TCZ and ADA group (p<0.0001). Treatment with TCZ provided better results in cost per response than ADA over 24 weeks in terms of ACR response (ACR20 €8,105 and €11,553; ACR50 €11,162 and €20,382; ACR70 €15,965 and €31,705) and DAS 28 remission €13,509 and €54,352 respectively. TCZ was dominant over ADA in ACR response and DAS28 remission. Sensitivity analysis confirmed the stability of the results. CONCLUSIONS: The results of this analysis suggest that TCZ monotherapy represents an efficient and cost-effective strategy vs. ADA in Spain, for treating RA patients who are MTX intolerant/contraindicated.