Prevalence of asthma has risen gradually in past 30 yr in Taiwan, but less is known about the trend of asthma hospitalization and different hospitalization patterns between children and adult groups in the Chinese population. The implementation of National Health Insurance (NHI) in Taiwan was in 1995, and it covered health care for >96% of the population. Using NHI data from 1996 to 2002, we investigated the admission rate, length of stay, cost and the readmission rate of hospitalization with primary diagnosis of asthma in this period. We also compare the difference between the children group (<18 yr old) and adult group (> or =18 yr old). The average incidence of hospitalization in the age group below 18 was 105.0 cases per 100,000 children, and was 116.7 per 100,000 population in the adult group during that period. It increased by 6.5% annually in the children group, though it was 0.1% annually in the adult group. The hospitalization days were 3.6 +/- 2.4 days in the children group, and were 8.2 +/- 8.9 days of those age > or =18 (p < 0.0001). The hospitalization cost was $288.7 +/- $292.9 and $717.5 +/- $1409.4, respectively (p < 0.0001). Autumn was the most frequent admission season in the children group, but the winter season was the most common in the adult group. The average readmission rate in this period was 20.4%. It was 13.0% in the children group, and was 22.6% in the adult group (p < 0.0001). The general hospitalization rate of asthma in the children group was lower than the adult group. It increased significantly in the children group from 1996 to 2002, but the admission cost rose prominently in the adult group during the same period. The hospitalization days, admission cost, and readmission rate were also significantly lower in the children group.