Asthma is the most frequent reason for preventable hospital admissions among children. During 1980-1993, national asthma surveillance demonstrated increasing rates of hospital admission for persons aged <25 years. These increasing rates could be attributed to an increase in either the number of persons admitted, readmitted, or both. To determine the number of persons with asthma sufficiently severe to require hospitalization and to characterize admission/readmission patterns for persons with asthma, the Wisconsin Department of Health and Family Services (WDHFS) analyzed data from the Wisconsin Asthma Surveillance System (WASS). This report summarizes the findings from WASS, which indicate that, during 1991-1995, an annual average of 18% of all asthma admissions among Wisconsin residents aged <25 years were readmissions.