It is also among the top five causes of death for everyone aged below 64, the Australian Institute of Health and Welfare has found.

Heart disease remains Australia's biggest killer across all ages.

The institute has tracked causes of death across the country in a major report released on Wednesday.

It found one in five Australians had a mental health condition and men were more likely to die by suicide than women.

Women were more likely to self-harm, with girls in their late teens the most likely to be hospitalised for intentionally hurting themselves.

Aboriginal and Torres Strait Islander people were almost twice as likely to die by suicide than non-Indigenous people.

The institute collated a range of data sets for its report, which also found one in eight Australians considered suicide in 2007.

More than 400 serving and ex-defence personnel died by suicide between 2001 and 2017, with veterans 18 per cent more likely than the general population.

The report contained some projections about the impact of domestic violence on suicide rates.

If domestic violence was eradicated by 2015, there would have been almost 20 per cent fewer suicides and self-harm injuries among women aged 15 and over.

There would also have been 41 per cent fewer homicides or violent crimes where the victims were women, the AIHW found.

The government spent $400 per person on mental health services in 2017/18, a slight rise on previous years.

Nearly two-thirds of people who visited a GP had psychological concerns, and one in 10 Australians accessed subsidised mental health services in 2018/19.

One in six Australians are on mental health-related prescriptions, with nearly three-quarters of those for anti-depressants.

The AIHW also shed light on physical health issues including obesity.

Nearly half of Australians live with a chronic health condition, most of which could be addressed through diet and exercise.

Two-thirds of adults and one-quarter of children are overweight or obese.

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Australian Associated Press