OBJECTIVES: Rheumatoid arthritis (RA) is a chronic, autoimmune inflammatory disease imposing a great burden on individuals and society, highlight by the introduction of new expensive biologics within this decade. This study compared the trend of health care expenditures and biologics costs due to rheumatoid arthritis from 1999-2009.  METHODS: This study was based on data from the National Health Insurance Research Database (NHIRD) released by the National Health Research Institute, which representing 99% of the entire population of Taiwan. We identified all patients by both with a primary diagnosed code ICD-9-CM 714.0 and with RA Catastrophic Illness certificate.  Patients who fulfilled the American College of Rheumatology criteria for the classification of RA are qualified to register in Catastrophic Illness file and can benefit for waiving the outpatient registration fee. The indication for reimbursement the biologics were DAS28³a5.1 for two continuous measures 1 month apart in Taiwan. RESULTS:  After adjusting by using WHO 2000 population, we found the incidence rate of RA is stable around 0.01% from 1999 to 2009 in Taiwan. However the prevalence rate is increasing from 0.07% to 1.13%. The average annual growth rates of total medication cost for RA patients (51.6%) are higher than the growth rates of total treatment cost for RA patient (36.7%) during the study period from 1999 to 2009. In addition, Outpatient drug cost growth rates (11.5%-44.1%) were much higher than that of inpatient drug growth rates (2.4%-26.7%) during this period. Enbrel was reimbursed by the National Health Insurance since 2003 and next year it reflected an 11.6% growth rate in expenditure.  Although there are three biologics reimbursed by NHI for qualified RA patients, Enbrel dominates on the market. CONCLUSIONS: The introduction of biologics may benefit to the decreasing rate of inpatient admission and costs.