To (1) estimate the lifetime and 12-month prevalence of self-harm without suicide intent in young people aged 12–17 years, (2) describe the co-morbidity of these behaviours with mental illness and (3) describe their co-variation with key social and demographic variables.

A nationally representative random sample of households with children aged 4–17 years recruited in 2013–2014. The survey response rate was 55% with 6310 parents and carers of eligible households participating. In addition, 2967 (89%) of young people aged 11–17 completed a self-report questionnaire with 2653 of the 12- to 17-year-olds completing questions about self-harm behaviour.

In any 12-month period, about 8% of all 12- to 17-year-olds (an estimated 137,000 12- to 17-year-olds) report engaging in self-harming behaviour without suicide intent. This prevalence increases with age to 11.6% in 16- to 17-year-olds. Eighteen percent (18.8%; 95% confidence interval [CI] = [14.5, 23.0]) of all 12- to 17-year-old young people with any mental health disorder measured by parent or carer report said that they had engaged in self-harm in the past 12 months. Among young people who were measured by self-report and met criteria for the Diagnostic and Statistical Manual of Mental Disorders’ major depressive disorder almost half (46.6%; 95% CI = [40.0, 53.1]) also reported that they had engaged in self-harm in the past 12 months. Suicide risk among those who self-harm is significantly elevated relative to the general population.

The demonstrated higher risks in these young people for continued harm or possible death support the need for ongoing initiatives to reduce self-harm through mental health promotion, improved mental health literacy and continuing mental health reform to ensure services are accessible to, and meet the needs of families and young persons.