OBJECTIVES: Little is known about asthma readmissions within 28 days over time by age or gender. We explored trends in childhood asthma hospital readmission rates over time by age, gender and season. METHODS: Using a large database of 53,156 childhood admissions with a primary diagnosis of asthma from the Department of Health Victoria Australia for 1997-2009, we explored asthma hospital readmissions rates by seasonality, gender and age (2-18 years) using chi square tests, logistic regression models and graphical techniques. RESULTS: Approximately 9459 (28%) of the children had two or more admissions over the whole study period, contributing to 55% (29,056/53,156) of all admissions. Approximately 5% of admissions were repeat admission within 28 days. Over time, despite a decline in asthma incidence, the rate of readmission within 28 days increased, particularly in the 2-12 year age groups. Girls were at greater risk of readmission within 28 days (odds ratio [OR] = 1.15; 95% CI: 1.004-1.32; p = 0.04) and 12 months (OR = 1.11; 95% CI: 1.05-1.19; p = 0.001). Grass pollen season was associated with readmissions within 28 days, but only in boys (p = 0.01). CONCLUSION: Over time, despite a fall in asthma incidence, readmission rates for childhood asthma significantly increased in younger age groups with girls at a higher risk of being readmitted than boys. Increased risk of repeat admission for boys was observed during the grass pollen season. These findings highlight high-risk groups, which has implications for both clinical services and patient care. More detailed monitoring of readmission rates amongst various risk groups over time is required.