Aim: Readmission of paediatric trauma patients is associated with increased hospital length of stay, additional operative procedures and significant costs to the health-care system. The rates and causes of readmission of paediatric trauma patients are not well reported outside of the USA or single centres. This nation-wide study is the first in Australia to examine the readmission rates, costs and characteristics of Australian paediatric trauma patients. Methods: This was a retrospective examination of linked hospitalisation and mortality data for injured children aged 16 or younger from 1 July 2001 to 30 June 2012, readmitted to hospital within 28 days of discharge. Data including injury severity, nature of injury, episodes of care and costs were extracted from hospitalisation data. Results: There were 37 603 injury children aged ≤16 years readmitted to hospital within 28 days during the 10-year period, a readmission rate of 5.5%. The most common principal injury requiring readmission was fracture (52.6%) and burns (19.3%). A total of 66% of all patients had a readmission diagnosis of injury, complication of their initial injury or complication of surgical and medical care; 30% were readmitted for a specific procedure or follow-up care. The total cost of readmissions was AU$108 million. Conclusions: Hospital readmission rates of paediatric trauma patients in Australia are due to injury or a complication of injury and are associated with significant costs. Early identification of at-risk patients and the prevention of complications are needed to prevent the ongoing burden of readmission.