To (1) estimate the lifetime and 12-month prevalence of suicidal behaviours in Australian young people aged 12–17 years, (2) describe their co-morbidity with mental illness and (3) describe the co-variation of these estimates with social and demographic variables.

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

In any 12-month period, about 2.4% or 41,400 young people would have made a suicide attempt. About 7.5% of 12- to 17-year-olds report having suicidal ideation, 5.2% making a plan and less than 1% (0.6%) receiving medical treatment for an attempt. The presence of a mental disorder shows the largest significant association with lifetime and 12-month suicidal behaviour, along with age, gender, sole parent family status and poor family functioning. Of young people with a major depressive disorder, 19.7% reported making a suicide attempt within the previous 12 months. There are also significant elevations in the proportions of young people reporting suicidal behaviour who have anxiety and conduct disorders.

Mental disorders should be a leading intervention point for suicide prevention both in the primary health sector and in the mental health sector specifically. The associations examined here also suggest that efforts to assist sole parent and/or dysfunctional families would be worthy areas in which to target these efforts.