To quantify the impact on the Western Australian health care system of hospitalisations due to interpersonal violence, and to identify risk factors for a repeat hospital admission for interpersonal violence.

A population-based, retrospective study of interpersonal violence in WA using linked data (1990–2004) from the Western Australian Mortality Database, the Hospital Morbidity Data System and the Mental Health Information System.

Number of hospitalisations and associated length of stay; risk factors for repeat hospitalisation.

Over the period 1990–2004, there were 36 934 hospital admissions due to interpersonal violence, with 11 507 of these hospitalisations due to a subsequent episode of interpersonal violence. The average length of stay was 2.6 days (SD, 4.9 days). People who were more likely to be readmitted for interpersonal violence included women (adjusted hazard ratio [AHR], 1.31; 95% CI, 1.23–1.39), Indigenous people (AHR, 1.37; 95% CI, 1.28–1.46) and patients with a mental illness (AHR, 1.46; 95% CI, 1.37–1.54). People with more affluent backgrounds tended to have a lower risk of being readmitted than people in the most disadvantaged socioeconomic group.

Greater priority should be directed towards the primary prevention of violence. Groups at high risk, such as women, Indigenous people and those with a mental illness, should be targeted for special attention.