Abstract: Objective: To describe rates of hospitalisation for head injury due to assault among Indigenous and non-Indigenous Australians. Design, setting and participants: Secondary analysis of routinely collected hospital morbidity data for 42 874 inpatients at public and private hospitals in Queensland, Western Australia, South Australia and the Northern Territory for the 6-year period 1 July 1999 – 30 June 2005. Main outcome measures: Rates per 100 000 population of head injury due to assault by Indigenous status, age, sex and location of residence. Results: The overall rate of head injury due to assault was 60.4 per 100 000 population (95% CI, 59.8–60.9). The rate among the Indigenous population was 854.8 per 100 000 (95% CI, 841.0–868.9), 21 times that among the non-Indigenous population (40.7 per 100 000; 95% CI, 40.2–41.2). Most Indigenous (88%) and non-Indigenous (83%) victims of head injury due to assault were aged between 15 and 44 years. The peak incidence among the Indigenous population was in the 30–34-year age group, whereas that among the non-Indigenous population was in the 20–24-year age group. Indigenous females experienced 69 times the injury rate experienced by non-Indigenous females. Conclusions: Indigenous people, particularly women, were disproportionately represented among those hospitalised for head injury due to assault. Head injury imposes a substantial burden of care on individuals and communities. Along with the costs of treating head injury, these are good reasons to strengthen efforts to prevent head injury generally, with special attention to high-risk population segments.