OBJECTIVES: Adalimumab is a human anti-TNF monoclonal antibody for the treatment of RA. This study was designed to assess the cost-effectiveness of adalimumab and the other biologic agents compared with conventional disease-modifying anti-rheumatic drugs (DMARDs) in patients with moderate/severe RA. METHODS: A Monte-Carlo patient-level simulation was developed to model patients' Health Assessment Questionnaire (HAQ) scores over a lifetime horizon. Efficacy data were taken from published literature and quality adjusted life years (QALYs) were de-rived from HAQ-utility relationships. Both direct costs (e.g. drug, administration, moni-toring, hospitalizations etc.) and indirect costs were calculated for each patient. Discount-ing was applied at 5% for both costs and effectiveness. RESULTS: Total discounted costs for adalimumab were 1,506,869 DKK, while costs of DMARDs were 1,398,958 DKK. Effectiveness amounted to 2.23 vs. 1.22 QALYs for adalimumab and DMARD-therapy, respectively. Thus, the incremental cost-effectiveness ratio (ICER) for adalimumab versus DMARD is 289,005 DKK per QALY. Infliximab and etanercept generated fewer QALYs than adalimumab, and had ICERs vs DMARDs, of 321,723 DKK and 306,990 DKK per QALY, respectively. CONCLUSION: This was the first health economic analysis of RA biologics in Denmark. The results suggest that adalimumab is a cost-effective treatment option for patients with RA and is more cost-effective than infliximab and etanercept.