Studies of asthma admissions in the St. Louis metropolitan area have disclosed substantial numbers of children with readmissions. To determine the magnitude of readmissions and attributes of children with readmissions, a retrospective analysis of 8,761 children with 14,905 asthma hospitalizations for January 1, 1990 through December 31, 1999 at the two university affiliated children's hospitals in St. Louis was undertaken. Patient attributes of age, sex, race/ethnicity, residence, payor status, length of stay, and month of admission were compared between patients admitted once during that period and patients admitted multiple times. Main outcome measures were the total number of admissions and time to readmission during the study interval. A Lin, Wei, Yang, and Ying model of time to readmission showed that African-American children with Medicaid or no insurance are at higher risk of readmission (risk ratio 1.28) than are African-American patients with commercial insurance or white/other race/ethnicity patients regardless of insurance. Probability of readmission increased from 30% after a first admission, 46% after a second, and 59% after a third. Prior admission was a more specific indicator of readmission with greater positive predictive value than ethnicity or insurance status or their combination.