OBJECTIVES:   Ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (nr-axSpA) are part of a group of inflammatory rheumatologic diseases. The economic and humanistic burden entailed by these conditions is significant. Certolizumab pegol (CZP) and adalimumab (ADA) are the only anti-TNFs approved for both entities. We aimed to assess their costs/outcomes from the perspective of the Mexican public health system in accordance with local HTA requirements. METHODS: The competing interventions were CZP and ADA in approved dosages. We used a decision tree and applied indirect treatment comparison techniques (Bucher´s method) to several outcomes, with BASDAI50 considered the primary efficacy measure. The time horizon for nr-axSpA population was 12 weeks, while the AS analyses were conducted to 12/24 weeks. Only drug acquisition cost was analyzed. An additional cost comparison was undertaken assuming similar long term efficacy with all patients receiving the treatments for 3 years (estimated treatment duration when these agents are administered for the first time). A 5% annual discount rate was applied from Year 2 and beyond. Costs are reported in Mexican Pesos for the cost year 2016 (€1=19.8441 MXN). Deterministic and probabilistic sensitivity analyses were performed. RESULTS: CZP was more effective than ADA in nr-axSpA ≥50% in BASDAI (CZP 200mg/400mg 47.9%–45% respectively versus ADA 40mg 35.2%) and exhibited similar effectiveness in AS. The costs per patient at 12/24 weeks were lower with CZP ($38,120/$60,992) than with ADA ($42,793/$79,472), with potential savings equivalent to 11% and 23%, respectively. Using CZP instead of ADA might lead to net savings of $161,949 (35%) per patient over a 3-year period. Results were robust to plausible variations of parameters. CZP was either dominant or cost-effective in 99.4% of the second-order MC simulations. CONCLUSIONS: In comparison to ADA, CZP may provide significant savings with at least similar effectiveness for the treatment of nr-axSpA and AS.