OBJECTIVES: There was still no pharmacoepidemiologic study of tumor necrosis factor antagonist (Anti-TNF) in Taiwan. We analysis the drug cost and prescription pattern of anti-TNF agents, and the change of prescription pattern of tradition disease-modified anti-rheumatic drug (DMARD) when anti-TNF used.      METHODS: This study utilizes National Health Insurance Database which cover more than 99% population in Taiwan. We analysis of the direct medical cost for RA patients from 1996 to 2007, and prescribe pattern of disease-modified anti-rheumatic drug (DMARD) and anti-TNF agents. RESULTS: The cost of anti-TNF agents accounted for 25% of total direct cost. But there was only about 5% RA patients been treated with this drug in Taiwan. The mean age of anti-TNF user was younger, but sex distribution seen no statistically difference in user and non-user group. In patients with anti-TNF use, the combined use of DMARD was decreased markedly. However, there is still some proportion of anti-TNF user have full dosage of DMARD treatment which suggest the possibility of inadequate response to anti-TNF agents in the population CONCLUSIONS: The percentage of anti-TNF agent use in RA patients is relative low in Taiwan. Some proportion of anti-TNF user still need full dosage DMARD and it may suggest the possibility of inadequate to anti-TNF agents in this group.