The National Health Insurance (NHI) program was officially launched on March 1th, 1995, in Taiwan for ten years. The balance of revenues and expenditure was stable initially, but a deficit was shown since 1998. Health-related retrospective databases, in particular claims databases, continue to be an important data source for outcomes research. OBJECTIVE: 1) To compare the asthma prevalence from the consecutive claimed-database to published results. 2) To understand trends of medical resources utilization of asthma in Taiwan. 3) To understand the improvement of asthmatic care in Taiwan. METHODS: During the year 1998 to 2002, claims with primary and secondary diagnosis of asthma in their ICD-9-CM code and A-code were obtained and then sorted per person to obtain their whole medical resource utilization. Those data files included ambulatory care expenditures by visits, details of ambulatory care orders, inpatient expenditures by admissions and details of inpatient orders. The STATA 8.0 and SAS 8.2 computer softwares were used to perform the analysis. RESULTS: 1) The prevalence of asthmatic patients form 1998 to 2002, from primary diagnosis, was 8.84%, 3.48%, 2.24%, 2.20% and 2.15%, respectively. 2)Number of Outpatient visited per person per year was from 2.07(1998) to 3.17(2002). Average prescription days per person: from 7.25(1998) to 12.08(2002). Number of hospitalization per person per year: from 0.02(1998) to 0.07(2002). Number of emergency visited per person per year: from 0.05(1998) to 0.14(2002). 3)Total cost per year: US$ 10, 7.2, 5.9, 6.3 and 6.9 million dollars. 4) The ratio of drug costs/total costs about 45%. CONCLUSIONS: Condition of asthmatic outpatient care was improving and inpatient care was worsen. The ratio of drug costs plays an important role in asthmatic care.