OBJECTIVES: This study aimed at assessing the changes in healthcare utilization and costs between patients treated with conventional synthetic and biological disease modifying antirhumatic drugs (csDMARD and bDMARD) for rheumatoid arthritis (RA) in Taiwan. METHODS: Two cohorts of severe RA patients were identified from National Health Insurance claims database. The csDMARD cohort was patients who had medication claim for cyclosporine ≥ 50 mg/day with concomitant use of ≥ 2 csDMARDs for ≥ 28 days within 56 days after cyclosporine use during 1997-2003 (N=1,569) . After csDMARD cohort was determined, the bDMARD cohort was selected if patients had ≥ 1 claim for bDMARD during 2003-2011 (N=1,530). The index date was the date with the first qualifying claim. Patients were followed up for maximum of 10 years, or death, switched to bDMARDs (for csDMARD only), or end of 2013, whichever came first. Per-patient-per-year (PPPY) annual healthcare utilization and costs were calculated by bootstrapping with 1,000 nonparametric replications drawn from the source cohorts. Annual incremental utilization and costs for csDMARD and bDMARD cohorts were compared. RESULTS: Incremental number of hospitalization days decreased by 75% (from 2.3 days for csDMARD to 0.58 day for bDMARD). The incremental total costs and RA medication costs were increased by 3.66 times (US$9,081 vs. US$2,481) and 4.78 times (US$8,992 vs. US$1,883), respectively, for bDMARD compared to csDMARD. However, the sum of incremental healthcare utilization costs and incremental non-RA medication costs was decreased by 64% (from US$1,302 for csDMARD to US$467 for bDMARD). CONCLUSIONS: The introduction of biologics in the treatment of RA has significantly reduced the hospitalization days for RA patients. Incremental costs of healthcare utilization and non-RA medication also decreased for bDMARD compared to csDMARD.